Electronic camera with self-adjusting flash and image-capture sensitivity

ABSTRACT

An electronic camera includes: an image-capturing unit with variable image-capturing sensitivity, which captures an image of a subject through a photographic lens; a brightness detection unit that detects subject brightness; an exposure calculation unit that executes an exposure calculation by using the image-capturing sensitivity set at the image-capturing unit and the detected subject brightness; a flash quantity calculation unit that calculates a main flash quantity for a flash unit that illuminates the subject when capturing an image thereof; and a sensitivity adjusting unit that adjusts the image-capturing sensitivity so as to achieve optimal exposure with a main flash quantity within a flash quantity control range of the flash unit when the main flash quantity calculated by the flash quantity calculation unit is outside the flash quantity control range. And if the image-capturing sensitivity has been adjusted by the sensitivity adjusting unit, the exposure calculation unit re-executes the exposure calculation.

This is a Continuation of application Ser. No. 11/082,065 filed Mar. 17,2005. The disclosure of the prior application is hereby incorporated byreference herein in its entirety.

INCORPORATION BY REFERENCE

The disclosures of the following priority applications are hereinincorporated by reference:

Japanese Patent Application No. 2004-112248 filed Apr. 6, 2004Japanese Patent Application No. 2004-163288 filed Jun. 1, 2004

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic camera that captures asubject image by using an image-capturing device.

2. Description of Related Art

An apex calculation known in the related art is executed to calculatethe optimal exposure quantity to be achieved in a camera as expressed in(1) below by using an aperture value AV of the photographic lens, ashutter speed (exposure period) TV, a subject brightness BV and anexposure sensitivity SV.

EV=AV+TV=BV+SV  (1)

EV in the expression above represents the exposure quantity. In a silverhalide camera in which SV is determined by the sensitivity of the filmbeing used, the aperture value AV and the shutter speed TV arecalculated in correspondence to the subject brightness BV so as toachieve the optimal exposure. In the case of an electronic camera whichallows the gains at the image-capturing device to be varied (see, forinstance, Japanese Laid Open Patent Application No. H 11-150679), theaperture value AV, the shutter speed TV and the image-capturingsensitivity SV can be determined in correspondence to the subjectbrightness BV as long as the gain at the image-capturing device, i.e.,the exposure sensitivity (image-capturing sensitivity) SV is variable.

SUMMARY OF THE INVENTION

Generally speaking, the brightness level of a main subject is often lowif the main subj ect needs to be illuminated with flash light emittedfrom an illuminating device during a photographing operation. When thebrightness of the main subject is low, the image-capturing sensitivitySV is adjusted to a higher level through the exposure calculationexpressed as in (1) above. There is a concern that the main subject maybe overexposed if it is illuminated with flash light from theilluminating device after the image-capturing sensitivity SV is adjustedas described above. In addition, in an image with scenery in thebackground obtained through a fill-in flash (daylight synchronized)photographing operation performed under backlight conditions, the imageportion other than the main subject, such as the background, may beoverexposed even if the main subject is exposed to the correct extent.

According to the 1st aspect of the invention, an electronic cameracomprises: an image-capturing unit with variable image-capturingsensitivity, which captures an image of a subject through a photographiclens; a brightness detection unit that detects subject brightness; anexposure calculation unit that executes an exposure calculation byusing, at least, the image-capturing sensitivity set at theimage-capturing unit and the subject brightness having been detected; aflash quantity calculation unit that calculates a main flash quantityfor a flash unit that illuminates the subject when capturing an imagethereof; and a sensitivity adjusting unit that adjusts theimage-capturing sensitivity so as to achieve optimal exposure with amain flash quantity within a flash quantity control range of the flashunit when the main flash quantity having been calculated by the flashquantity calculation unit is outside the flash quantity control range,and if the image-capturing sensitivity has been adjusted by thesensitivity adjusting unit, the exposure calculation unit re-executesthe exposure calculation.

According to the 2nd aspect of the invention, in the electronic cameraaccording to the 1st aspect, it is preferred that: there is furtherprovided a reflected light detection unit that detects reflected lightfrom the subject when the flash unit executes a preliminary flashemission; and the flash quantity calculation unit calculates the mainflash quantity needed for an image-capturing operation based upon adetection signal obtained at the reflected light detection unit in thepreliminary flash emission and the image-capturing sensitivity currentlyset at the image-capturing unit.

According to the 3rd aspect of the invention, in the electronic cameraaccording to the 1st aspect, it is preferred that the exposurecalculation unit alters an exposure time period which is currently setwhen the exposure calculation is re-executed.

According to the 4th aspect of the invention, in the electronic cameraaccording to the 1st aspect, it is preferred that the exposurecalculation unit does not re-execute the exposure calculation if thecamera is set in a shutter speed priority automatic exposure calculationmode.

According to the 5th aspect of the invention, in the electronic cameraaccording to the 1st aspect, it is preferred that the exposurecalculation unit does not re-execute the exposure calculation if thecamera is set in a manual exposure mode.

According to the 6th aspect of the invention, in the electronic cameraaccording to the 1st aspect, it is preferred that when re-executing theexposure calculation, the exposure calculation unit adjusts at least oneof an aperture value and a shutter speed set in the camera if the camerais set in a program automatic exposure calculation mode, adjusts theaperture value if the camera is set in a shutter speed priorityautomatic exposure calculation mode and adjusts the shutter speed if thecamera is set in an aperture priority automatic exposure calculationmode; and the exposure calculation unit does not re-execute the exposurecalculation if the camera is set in a manual exposure mode.

According to the 7th aspect of the invention, an electronic cameracomprises: an image-capturing device that captures a subject imagethrough a photographic lens; a brightness detection unit that detectssubject brightness; a first exposure calculation unit that executes anexposure calculation by using at least an exposure sensitivity currentlyset for the image-capturing device and the subject brightness havingbeen detected among the exposure sensitivity currently set for theimage-capturing device, an exposure time length currently set for theimage-capturing device, an currently set aperture value and the detectedsubject brightness; a reflected light detection unit that detectsreflected light from the main subject when light is emitted from a flashemitting unit which executes a main flash emission to illuminate thesubject during a photographing operation and a preliminary flashemission to illuminate the subject prior to the photographing operation;a flash quantity calculation unit that calculates a main flash quantitywhich needs to be achieved for the photographing operation based upon adetection signal obtained at the reflected light detection unit duringthe preliminary flash emission and the exposure sensitivity; asensitivity adjusting unit that adjusts the currently set exposuresensitivity to an exposure sensitivity needed to achieve optimalexposure of a main subject with a main flash quantity within a flashquantity control range if the main flash quantity having been calculatedby the flash quantity calculation unit is outside the flash quantitycontrol range of the flash emitting unit; and a second exposurecalculation unit that re-executes the exposure calculation by adjustingat least one of the exposure time length and the aperture value so as toachieve optimal exposure for objects other than the main subject whenthe exposure sensitivity has been adjusted by the sensitivity adjustingunit.

According to the 8th aspect of the invention, an electronic cameracomprises: an image-capturing unit with variable image-capturingsensitivity, which captures an image of a subject through a photographiclens; a brightness detection unit that detects a subject brightness; afirst calculation unit that calculates an ambient light over/underextent by using an image-capturing sensitivity set for theimage-capturing unit, an exposure time length set for an image-capturingoperation, an aperture value set for the image-capturing operation andthe subject brightness having been detected; a second calculation unitthat calculates a main flash quantity to be achieved at a flash unitwhich illuminates the subject during the image-capturing operation; athird calculation unit that calculates a correction quantity indicatingan extent by which the currently set image-capturing sensitivity shouldbe corrected so as to achieve optimal exposure of the subject with amain flash quantity within a variable flash quantity range if the mainflash quantity having been calculated by the second calculation unit isoutside the variable flash quantity range of the flash unit; and asensitivity adjusting unit that adjusts the currently setimage-capturing sensitivity based upon the correction quantity havingbeen calculated by the third calculation unit and the ambient lightover/under extent having been calculated by the first calculation unit.

According to the 9th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that: there is furtherprovided a reflected light detection unit that detects reflected lightfrom the subject when the flash unit executes a preliminary flashemission; and the second calculation unit calculates the main flashquantity needed for an image-capturing operation based upon a detectionsignal obtained at the reflected light detection unit during thepreliminary flash emission and the image-capturing sensitivity currentlyset for the image-capturing unit.

According to the 10th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that if the correctionquantity indicates an increase from the currently set image-capturingsensitivity, the sensitivity adjusting unit adjusts the image-capturingsensitivity by restricting an extent of change in the image-capturingsensitivity in correspondence to the ambient light over/under extent.

According to the 11th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that if the correctionquantity indicates an increase from the currently set image-capturingsensitivity and the ambient light over/under extent indicates thatsufficient ambient light is available, the sensitivity adjusting unitdoes not alter the image-capturing sensitivity.

According to the 12th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that if the correctionquantity indicates an increase from the currently set image-capturingsensitivity and an extent of ambient light insufficiency indicated bythe ambient light over/under extent is smaller than an extent ofunder-exposure corresponding to the correction quantity, the sensitivityadjusting unit adjusts the image-capturing sensitivity based upon theambient light over/under extent.

According to the 13th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that if the correctionquantity indicates an increase from the currently set image-capturingsensitivity and an extent of ambient light insufficiency indicated bythe ambient light over/under extent is greater than an extent ofunder-exposure corresponding to the correction quantity, the sensitivityadjusting unit adjusts the image-capturing sensitivity based upon thecorrection quantity.

According to the 14th aspect of the invention, in the electronic cameraaccording to the 8th aspect, it is preferred that: the secondcalculation unit corrects the main flash quantity in correspondence to aflash control correction quantity currently set at the camera; and thethird calculation unit corrects the correction quantity incorrespondence to the currently set flash control correction quantity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the structure adopted in the electroniccamera achieved in a first embodiment of the present invention;

FIG. 2 presents a flowchart of the camera operation processing;

FIG. 3 presents a flowchart of the camera operation processing;

FIG. 4 presents a flowchart of the camera operation processing;

FIG. 5 presents a detailed flowchart of the setting processing;

FIG. 6 presents a detailed flowchart of the communication processing;

FIG. 7 presents a detailed flowchart of the exposure calculationprocessing A;

FIG. 8 presents a detailed flowchart of the exposure calculationprocessing A;

FIG. 9 presents a detailed flowchart of the display processing;

FIG. 10 presents a detailed flowchart of the image-capturing sequenceprocessing A;

FIG. 11 presents a detailed flowchart of the exposure calculationprocessing B executed when a flash unit is utilized;

FIG. 12 presents a detailed flowchart of the image-capturing sequenceprocessing B;

FIG. 13 presents a detailed flowchart of the image-capturing sequenceprocessing B;

FIG. 14 presents a detailed flowchart of the image-capturing sequenceprocessing B;

FIG. 15 presents a detailed flowchart of the image-capturing sequenceprocessing B;

FIG. 16 presents a detailed flowchart of the image-capturing sequenceprocessing C;

FIG. 17 presents a detailed flowchart of the image-capturing sequenceprocessing C;

FIG. 18 presents a detailed flowchart of the image-capturing sequenceprocessing C;

FIG. 19 presents a detailed flowchart of the image-capturing sequenceprocessing C;

FIG. 20 presents a detailed flowchart of the exposure calculationprocessing BB;

FIG. 21 is a program chart representing the operation executed whenneither flash unit is utilized;

FIG. 22 is a program chart representing the operation executed when aflash unit is utilized;

FIG. 23 presents a detailed flowchart of the exposure calculationprocessing BB1 in a second embodiment;

FIG. 24 presents a detailed flowchart of the exposure calculationprocessing BB2;

FIG. 25 presents a detailed flowchart of the exposure calculationprocessing BB3 in a third embodiment;

FIG. 26 presents a detailed flowchart of the exposure calculationprocessing BB3;

FIG. 27 presents a detailed flowchart of the exposure calculationprocessing BB3;

FIG. 28 presents a detailed flowchart of the exposure calculationprocessing BB3;

FIG. 29 presents a flowchart of a variation of the exposure calculationprocessing BB3;

FIG. 30 presents a flowchart of a variation of the exposure calculationprocessing BB3;

FIG. 31 is a block diagram of the structure adopted in the electroniccamera achieved in a fourth embodiment of the present invention;

FIG. 32 presents a flowchart of the camera operation processing executedby the arithmetic operation circuit; and

FIG. 33 presents a flowchart of the shutter release sequence processing.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following is an explanation of the preferred embodiments of thepresent invention, given in reference to the drawings.

First Embodiment

FIG. 1 is a block diagram of the structure adopted in an electroniccamera 1 achieved in the first embodiment of the present invention. Theelectronic camera 1 includes an internal flash unit, and an externalflash unit 11 is mounted at an accessory shoe (not shown). An arithmeticoperation circuit 101 is constituted with a microcomputer and the like.The arithmetic operation circuit 101 executes specific arithmeticoperations by using signals input thereto from various blocks to beexplained later and outputs control signals generated based upon thearithmetic operation results to the individual blocks. The arithmeticoperation circuit 101 further includes a communication circuit (notshown) which enables the arithmetic operation circuit 101 to communicatewith the external flash unit 11.

An image-capturing element 121 is constituted with a CCD image sensor orthe like. The image-capturing element 121 captures an image formed withsubject light having passed through an interchangeable lens L used forphotographing operations and outputs an image-capturing signal to an A/Dconversion circuit 122. The A/D conversion circuit 122 converts theanalog image-capturing signal to a digital signal. The image-capturingelement 121 and the A/D conversion circuit 122 are driven so as tooperate with specific timing by drive signals output from a timingcircuit 124.

An image processing circuit 123 may be constituted with an ASIC or thelike. In addition to executing image processing such as white balanceprocessing on image data resulting from the digital conversion, theimage processing circuit 123 executes compression processing forcompressing the image data having undergone the image processing in apredetermined format, decompression processing for decompressingcompressed image data and the like. In a buffer memory 125, image datato be processed at the image processing circuit 123 are temporarilystored. A recording medium 126 may be a detachable memory card that canbe loaded into and unloaded from the camera freely, for instance. Theimage data having undergone the image processing are recorded into therecording medium 126.

A position detection switch SW1 is a micro switch that detects theposition of the internal flash unit (not shown), i.e., whether it is ata storage position or it has been popped up to an operating position bya pop-up mechanism (not shown). One end of the position detection switchSW1 is grounded, whereas another end of the position detection switch isconnected to an input port of the arithmetic operation circuit 101. Theposition detection switch SW1 outputs an ON signal when the internalflash unit is at the operating position and outputs an OFF signal whenthe internal flash unit is at the storage position.

An emitted light quantity detection device 118 detects the quantity oflight emitted at a light emitting unit 44 of the internal flash unit andoutputs a detection signal to the arithmetic operation circuit 101. Theemitted light quantity detection is achieved by executing timeintegration of a light receiving signal generated upon receiving thelight having been initially emitted by the internal flash unit (or theexternal flash unit 11) and then having been reflected at the subject.

The light emitting unit 44 is a light emitting element in the internalflash unit. An internal flash unit light emission circuit 102 executeslight emission control by issuing a light emission start instruction anda light emission stop instruction for the light emitting unit 44 inresponse to commands from the arithmetic operation circuit 101. Theinternal flash unit light emission circuit 102, which includes a chargecircuit (not shown), starts a charge upon receiving a command from thearithmetic operation circuit 101 and outputs a complete signal as thecharge is completed.

A photometering device 103 detects the quantity of subject light passingthrough the photographic lens L and outputs a detection signal to thearithmetic operation circuit 101. The photometering device 103 adopts astructure which enables detection of the quantities of lightcorresponding to, for instance, five divided areas of the photographicfield. The aperture value of the photographic lens L is F2.8 (AV=3). Afocal point detection device 104 detects the state of the adjustment ofthe focal point position achieved with the photographic lens L andoutputs a detection signal to the arithmetic operation circuit 101.

A lens drive device 105 adjusts the focal point position of thephotographic lens L by driving a focus lens (not shown) in thephotographic lens L forward/backward along the optical axis in responseto a command is sued by the arithmetic operation circuit 101.

A halfway press switch SW2 interlocks with a shutter release operationbutton (not shown) and outputs a halfway press operation signal to thearithmetic operation circuit 101. The halfway press operation signalenters an ON state as the shutter release operation button is presseddown approximately halfway relative to its full stroke and shifts intoan OFF state when the shutter release operation button having been heldat the halfway position is released. A full press switch SW3 interlockswith the shutter release operation button (not shown) and outputs a fullpress operation signal to the arithmetic operation circuit 101. The fullpress operation signal enters an ON state as the shutter releaseoperation button is pressed down to the full stroke position and shiftsinto an OFF state when the shutter release operation button having beenheld down at the full stroke position is released.

A display device 111 displays photographing information such as thecurrent settings for the exposure mode, the sensitivity, the shutterspeed and the aperture in response to a command from the arithmeticoperation circuit 101.

The front curtain and the rear curtain (not shown) at a shutter 115 areheld and released independently of each other under control implementedby a shutter drive circuit 114. An X contact point switch SW5 enters anON state and outputs an ON signal as the front curtain at the shutter115 completes its run, and enters an OFF state and outputs an OFF signalhalfway through a charge of the shutter 115. An aperture positiondetection device 116 detects the aperture position corresponding to theaperture value and outputs a detection signal to the arithmeticoperation circuit 101. An aperture holding device 117 stops the aperturebeing driven and holds the aperture at the position corresponding to aspecific aperture value.

A motor drive circuit 112 implements drive control on a sequence motor113 in response to a command from the arithmetic operation circuit 101.The sequence motor 113, which constitutes a sequence drive device (notshown), raises/lowers a mirror (not shown), drives the aperture (notshown), charges the shutter 115 and the like. A sequence switch SW4,which is also part of the sequence drive device mentioned above,generates, for instance, the timing with which braking of the sequencemotor 113 is controlled.

An exposure mode setting operation member 106 outputs an operationsignal to the arithmetic operation circuit 101 in response to anexposure mode setting operation. Based upon the exposure mode settingoperation signal input thereto, the arithmetic operation circuit 101selects a program automatic exposure mode (P mode), a shutter speedpriority automatic exposure mode (S mode), an aperture priorityautomatic exposure mode (A mode) or a manual exposure mode (M mode).

A shutter speed setting operation member 107 outputs an operation signalto the arithmetic operation circuit 101 in response to a shutter speedsetting operation if the S mode or the M mode is currently selected forthe exposure mode, the arithmetic operation circuit 101 adjusts theshutter speed setting TVs based upon the shutter speed setting operationsignal input thereto. The apex value setting range may be, for instance,−5≦TVs≦13, i.e., 30 sec to 1/8000 sec.

An aperture value setting operation member 108 outputs an operationsignal to the arithmetic operation circuit 101 in response to anaperture value setting operation. When the A mode or the M mode iscurrently set for the exposure mode, the arithmetic operation circuit101 adjusts the aperture value setting AVs based upon the aperture valuesetting operation signal input thereto. The apex value setting range maybe, for instance, 3≦AVs≦9, i.e., F2.8 to F22.

A sensitivity automatic control mode setting operation member 109outputs an operation signal to the arithmetic operation circuit 101 inresponse to a setting operation. Based upon the sensitivity automaticcontrol mode setting operation signal input thereto, the arithmeticoperation circuit 101 sets and clears a sensitivity automatic controlmode. The sensitivity automatic control mode is an operation mode inwhich the control exposure is calculated by automatically adjusting theimage-capturing sensitivity SV (exposure sensitivity) in correspondenceto an exposure deviation ΔEV or the extent of excess or deficiency ofthe light emitted by the flash unit so as to achieve optimal exposure.The exposure deviation ΔEV represents the difference between the controlexposure and the optimal exposure. When the sensitivity automaticcontrol mode is not in effect, the control exposure is calculated so asto achieve the optimal exposure at the current image-capturingsensitivity setting SV.

A sensitivity setting operation member 110 outputs an operation signalto the arithmetic operation circuit 101 in response to animage-capturing sensitivity setting operation. The arithmetic operationcircuit 101 adjusts the setting for the image-capturing sensitivity atthe image-capturing element 121 based upon the image-capturingsensitivity setting operation signal input thereto. The image-capturingsensitivity may be selected in specific steps within a range equivalentto, for instance, ISO 100 to ISO 1600.

The external flash unit 11 includes a controller 201, a light emissioncircuit 202, a light emitting unit 11 a, a setting operation member 203and a display device 204. As the external flash unit 11 is mounted atthe accessory shoe (not shown) at the camera body 1, the arithmeticoperation circuit 101 at the camera body 1 and the external flash unit11 become connected through contact point terminals 10 a, 10 b and 10 c.The contact point terminal 10 a is a terminal for an X contact pointsignal generated through the X contact point switch SW5. The X contactpoint signal is output to the controller 201 via the contact pointterminal 10 a while a signal output is allowed by the arithmeticoperation circuit 101 but is not output to the controller 201 if thesignal output is prohibited. The contact point terminal 10 b is a GNDterminal provided to equalize the electrical ground potentials at thecamera body 1 and the external flash unit 11. The contact point terminal10 c is a communication terminal through which the camera body 1 and theexternal flash unit 11 communicate with each other.

The controller 201 is constituted with a microcomputer and the like. Thecontroller 201 executes specific arithmetic operations by using signalsinput thereto from various blocks in the external flash unit 11 andoutputs control signals generated based upon the arithmetic operationresults to the individual blocks in the external flash unit 11. Inaddition, the controller 201 engages in communication with thearithmetic operation circuit 101 via the contact point terminal 10 c toreceive a preliminary light emission instruction and a signal indicatingthe flash quantity (or flash output value) from the arithmetic operationcircuit 101 and also to transmit a signal indicating the specific lightemission mode set at the external flash unit 11 and signal indicatingthe bounce condition and the like. The controller 201 also issues alight emission instruction for the light emission circuit 202 uponreceiving an X contact point ON signal input thereto via the contactpoint terminal 10 a.

The light emission circuit 202 implements light emission control byissuing a light emission start instruction and a light emission stopinstruction for the light emitting unit 11 a of the external flash unit11 in response to commands issued by the controller 201. The lightemission circuit 202, which includes a charge circuit (not shown),starts a charge upon receiving a charge start operation signal from thesetting operation member 203 and outputs a complete signal to thecontroller 201 as the charge is completed.

The setting operation member 203 is a switch through which the chargestart instruction is issued, the light emission mode is set and thelike. A display indicating the charge state of the external flash unit11 is brought up at the display device 204. In addition, informationindicating the current light emission mode setting is displayed at thedisplay device 204.

The feature characterizing the present invention is the exposure controlimplemented when the electronic camera 1 is set in the sensitivityautomatic control mode, and more specifically, it is characterized inthat the exposure calculation is re-executed with the sensitivityadjusted when a flash unit is utilized.

The camera operation processing executed by the arithmetic operationcircuit 101 in the electronic camera 1 is now explained in reference tothe flowchart presented in FIGS. 2 through 4. The program in conformanceto which the processing in the flowchart in FIGS. 2 through 4 isexecuted is started up as a battery (now shown) is loaded into theelectronic camera 1. The electronic camera 1 engages in the followingthree primary operations.

1. The operation executed without utilizing the internal flash unit whenthe external flash unit 11 is not mounted at the camera body 1.2. The operation executed by utilizing the internal flash unitregardless of whether or not the external flash unit 11 is mounted atthe camera body 1.3. The operation executed by utilizing the external flash unit mountedat the camera body 1 without utilizing the internal flash unit.

The processing flows in FIGS. 2 through 4 respectively correspond tocases 1 through 3 described above.

In step S1 in FIG. 2, the arithmetic operation circuit 101 executes aninitial reset by setting a flag P to 0, a main flash quantity h for theexternal flash unit 11 to 0, a charge flag J to 0, a sensitivityautomatic control mode flag F to 0, a mode parameter M to 0, the shutterspeed setting TVs to 7 ( 1/125 sec), the aperture value setting AVs to 5(F5.6) and the sensitivity setting SVs to 7 (equivalent to ISO 400), andthen the operation proceeds to step S2. The flag P used to issue apreliminary light emission instruction for the external flash unit 11indicates that a preliminary light emission is to be executed when it isset to 1 and indicates that no preliminary light emission is to beexecuted when it is set to 0. The preliminary light emission may bereferred to as a pre-light emission or a preliminary flash emissioninstead. Based upon the light emitted in the preliminary light emission,which is executed for purposes of flash control, the flash quantity h tobe emitted in the main light emission during the photographing operation(during the charge storage) is determined through arithmetic operation.

The charge flag J is set to 1 when the charge at the internal flash unitlight emission circuit 102 is completed and is set to 0 if the charge isnot completed yet. The sensitivity automatic control mode flag S is setto 1 when the sensitivity automatic control mode is selected and is setto 0 when the sensitivity automatic control mode is cleared. The modeparameter M is set to 0 when the P mode is selected, is set to 1 whenthe S mode is selected, is set to 2 when the A mode is selected and isset to 3 when the M mode is selected. The apex value range of theimage-capturing sensitivity setting SVs in the electronic cameraachieved in the first embodiment is 5≦SVs≦9 (equivalent to ISO 100 toISO 1600).

In step S2, the arithmetic operation circuit 101 executes settingprocessing before proceeding to step S3. The setting processing is to beexplained in detail later. In step S3, the arithmetic operation circuit101 makes a decision as to whether or not the light emitting unit 44 ofthe internal flash unit is at the operating position. The arithmeticoperation circuit to 101 makes a negative decision in step S3 if an OFFsignal has been input from the position detection switch SW1 to proceedto step S4, whereas it makes an affirmative decision in step S3 if an ONsignal has been input from the position detection switch SW1 to proceedto step S21 in FIG. 3. The operation proceeds to step S4 when theinternal flash unit is at the storage position, whereas the operationproceeds to step S21 if the internal flash unit has been popped up tothe operating position. If the internal flash unit is at the storageposition, the arithmetic operation circuit 101 does not issue a lightemission instruction for the internal flash unit light emission circuit102 (does not allow light to be emitted).

In step S4, the arithmetic operation circuit 101 executes communicationprocessing to engage in communication with the controller 201 at theexternal flash unit 11, and then the operation proceeds to step S5. Thecommunication processing is to be explained in detail later.

In step S5, the arithmetic operation circuit 101 makes a decision as towhether or not a flag R is currently set to 1. The flag R is set to 1 ifcommunication has been achieved through the communication processing andis set to 0 if communication has not been achieved. The arithmeticoperation circuit 101 makes a negative decision in step S5 if R=0 toproceed to step S6, whereas it makes an affirmative decision in step S5if R=1 to proceed to step S51 in FIG. 4. The operation proceeds to stepS6 if the external flash unit 11 having a communication function is notmounted at the camera body 1, whereas the operation proceeds to step S51if the external flash unit 11 with the communication function is mountedat the camera body 1.

(When Neither Flash Unit is Utilized)

The processing executed in steps S6 through S15 corresponds to case 1described above. In step S6, the arithmetic operation circuit 101receives detection signals (photometering signals) input from thephotometering device 103, and then the operation proceeds to step S7. Instep S7, the arithmetic operation circuit 101 executes a photometricarithmetic operation by determining the quantities of light having beentransmitted through the lens (BVi-3) based upon the detection signalscorresponding to the individual areas defined by dividing thephotographic field to calculate the subject brightness By, and then theoperation proceeds to step S8. BVI indicates the subject brightness ineach area. 3 is subtracted from the value representing BVI since thelight is measured through the photographic lens L with the open aperturevalue of F2.8 (apex value AV=3). By executing an arithmetic operation ofthe known art based upon the subject brightness levels BVi in theindividual areas, the arithmetic operation circuit 101 determines thesubject brightness BV.

In step S8, the arithmetic operation circuit 101 executes processing forexposure calculation A before proceeding to step S9. The exposurecalculation processing A is to be explained in detail later. In step S9,the arithmetic operation circuit 101 executes display processing for thedisplay device 111 and the operation proceeds to step S10. The displayprocessing is to be described in detail later.

In step S10, the arithmetic operation circuit 101 outputs a command forthe focal point detection device 104 to detect the state of the focalpoint position adjustment achieved with the photographic lens L. Thearithmetic operation circuit 101 then calculates a defocusing quantityrepresenting the extent of defocusing of the focus lens based upon theresults of the detection executed by the focal point detection device104 and then the operation proceeds to step S11.

In step S11, the arithmetic operation circuit 101 makes a decision as towhether or not a halfway press operation has been performed. Thearithmetic operation circuit 101 makes an affirmative decision in stepS11 if an operation signal has been input from the halfway press switchSW2 to proceed to step S12, whereas it makes a negative decision in stepS11 if no operation signal has been input from the halfway press switchSW2 to return to step S2.

In step S12, the arithmetic operation circuit 101 calculates a lensdrive quantity based upon the defocusing quantity and then the operationproceeds to step S13. In step S13, the arithmetic operation circuit 101outputs a command for the lens drive device 105 to drive the focus lensin the photographic lens L by the lens drive quantity calculated in stepS12 so as to set the focus lens at a focus match position, beforeproceeding to step S14.

In step S14, the arithmetic operation circuit 101 makes a decision as towhether or not a full press operation (a shutter release) has beenperformed. The arithmetic operation circuit 101 makes an affirmativedecision in step S14 if an operation signal has been input from the fullpress switch SW3 to proceed to step S15, whereas it makes a negativedecision in step S14 if no operation signal has been input from the fullpress switch SW3 to return to step S2.

In step S14, the arithmetic operation circuit 101 executesimage-capturing sequence processing A, and then the operation returns tostep S2. The sequence of the photographing processing thus ends. Theprocessing executed for the image-capturing sequence A is to beexplained in detail later.

The setting processing is now explained in detail in reference to aflowchart presented in FIG. 5. In step S101 in FIG. 5, the arithmeticoperation circuit 101 makes a decision as to whether or not asensitivity change operation has been performed. The arithmeticoperation circuit 101 makes an affirmative decision in step S101 if anoperation signal has been input from the sensitivity setting operationmember 110 to proceed to step S102, whereas it makes a negative decisionin step S101 if no operation signal has been input from the sensitivitysetting operation member 110 to proceed to step S108.

In step S102, the arithmetic operation circuit 101 makes a decision asto whether or not the sensitivity is to be adjusted to a higher setting.The arithmetic operation circuit 101 makes an affirmative decision instep S102 if the operation signal from the sensitivity setting operationmember 110 indicates a sensitivity increase to proceed to step S103,whereas it makes a negative decision in step S102 if the operationsignal does not indicate a sensitivity increase to proceed to step S105.

In step S103, the arithmetic operation circuit 101 makes a decision asto whether or not the preadjustment SVs is 9. The arithmetic operationcircuit 101 makes an affirmative decision in step S103 if SVs=9 (if theimage-capturing sensitivity setting is equivalent to ISO 1600) to endthe setting processing and proceed to step S3 in FIG. 2. In thissituation, the sensitivity is set at the upper limit in the sensitivitysetting range and thus, the setting processing ends without furtherincreasing the sensitivity. If, on the other hand, SVs≠9, the arithmeticoperation circuit 101 makes a negative decision in step S103 to proceedto step S104. In step S104, the arithmetic operation circuit 101increments the image-capturing sensitivity setting SVs by 1 beforeending the setting processing and proceeding to step S3 in FIG. 2. As aresult, the image-capturing sensitivity setting is raised by one step.

In step S105, the arithmetic operation circuit 101 makes a decision asto whether or not the sensitivity is to be adjusted to a lower setting.The arithmetic operation circuit 101 makes an affirmative decision instep S105 if the operation signal from the sensitivity setting operationmember 110 indicates a sensitivity decrease to proceed to step S106.However, it makes a negative decision in step S105 if the operationsignal does not indicate a sensitivity decrease to end the settingprocessing and proceed to step S3 in FIG. 2.

In step S106, the arithmetic operation circuit 101 makes a decision asto whether or not the preadjustment SVs is 5. The arithmetic operationcircuit 101 makes an affirmative decision in step S106 if SVs=5 (if theimage-capturing sensitivity setting was equivalent to ISO 100) to endthe setting processing and proceed to step S3 in FIG. 2. In thissituation, the sensitivity is set at the lower limit in the sensitivitysetting range and thus, the setting processing ends without furtherdecreasing the sensitivity. If, on the other hand, SVs≠5, the arithmeticoperation circuit 101 makes a negative decision in step S106 to proceedto step S107. In step S107, the arithmetic operation circuit 101decrements the image-capturing sensitivity setting SVs by 1 beforeending the setting processing and proceeding to step S3 in FIG. 2. As aresult, the image-capturing sensitivity setting is lowered by one step.

In step S108 to which the operation proceeds after making a negativedecision in step S101 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not an exposure modechange operation has been performed. The arithmetic operation circuit101 makes an affirmative decision in step as 108 if an operation signalhas been input from the exposure mode setting operation member 106 toproceed to step S109, whereas it makes a negative decision in step S108if no operation signal has been input from the exposure mode settingoperation member 106 to proceed to step S116.

In step S109, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure mode setting prior to the change is the Pmode. The arithmetic operation circuit 101 makes an affirmative decisionin step S109 if M=0 (program automatic exposure mode) to proceed to stepS110, whereas it makes a negative decision in step S109 if M≠0 toproceed to step S111. In step S110, the arithmetic operation circuit 101sets the mode parameter M to 1 (5 mode) before ending the settingprocessing and proceeding to step S3 in FIG. 2.

In step S111, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure mode setting prior to the change is the Smode. The arithmetic operation circuit to 101 makes an affirmativedecision in step S111 if M=1 (shutter speed priority automatic exposuremode) to proceed to step S112, whereas it makes a negative decision instep S111 if M≠1 to proceed to step S113. In step S112, the arithmeticoperation circuit 101 sets the mode parameter M to 2 (A mode) beforeending the setting processing and proceeding to step S3 in FIG. 2.

In step S113, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure mode setting prior to the change is the Amode. The arithmetic operation circuit to 101 makes an affirmativedecision in step S113 if M=2 (aperture priority automatic exposure mode)to proceed to step S114, whereas it makes a negative decision in stepS113 if M≠2 to proceed to step S115. In step S114, the arithmeticoperation circuit 101 sets the mode parameter M to 3 (M mode) beforeending the setting processing and proceeding to step S3 in FIG. 2.

In step S115, the arithmetic operation circuit 101 sets the modeparameter M to 0 (P mode) before ending the setting processing andproceeding to step S3 in FIG. 2. Through the processing executed insteps S109 through S115 as described above, the exposure mode iscyclically changed in the order; P->S->A->M->P . . . , each time theexposure mode setting operation member 106 is operated.

In step S116 to which the operation proceeds after making a negativedecision in step S108, the arithmetic operation circuit 101 makes adecision as to whether or not the P mode is currently selected. Thearithmetic operation circuit 101 makes an affirmative decision in stepS116 if M=0 to end the setting processing and proceed to step S3 in FIG.2. In this situation, no setting operation for the shutter speed or theaperture value is executed. If M≠0, the arithmetic operation circuit 101makes a negative decision in step S116 to proceed to step S117.

In step S117, the arithmetic operation circuit 101 makes a decision asto whether or not the Anode is currently selected. The arithmeticoperation circuit 101 makes an affirmative in step S117 if M=2 toproceed to step S125. In this case, no setting operation for the shutterspeed is executed. The arithmetic operation circuit 101 makes a negativedecision in step S117 if M≠2 to proceed to step S118.

In step S118, the arithmetic operation circuit 101 makes a decision asto whether or not a shutter speed change operation has been performed.The arithmetic operation circuit 101 makes an affirmative decision instep S118 if an operation signal has been input from the shutter speedsetting operation member 107 to proceed to step S119, whereas it makes anegative decision in step S118 if no operation signal has been inputfrom the shutter speed setting operation member 107 to proceed to stepS125.

In step S119, the arithmetic operation circuit 101 makes a decision asto whether or not the shutter speed is to be adjusted to a higher speedsetting. The arithmetic operation circuit 101 makes an affirmativedecision in step S119 if the operation signal from the shutter speedsetting operation member 107 indicates a higher speed setting to proceedto step S120, whereas it makes a negative decision in step S119 if theoperation signal does not indicate a higher speed setting to proceed tostep S122.

In step S120, the arithmetic operation circuit 101 makes a decision asto whether or not the pre-adjustment TVs setting is 13. The arithmeticoperation circuit 101 makes an affirmative decision in step S120 ifTVs=13 (the shutter speed setting is 1/8000 sec) to end the settingprocessing and proceed to step S3 in FIG. 2. In this case, the shutterspeed setting is at the upper limit of the shutter speed setting rangeand thus, the setting processing ends without further raising theshutter speed. If, on the other hand, TVs≠13, the arithmetic operationcircuit 101 makes a negative decision in step S120 to proceed to stepS121. In step S121, the arithmetic operation circuit 101 increments theshutter speed setting TVs by 1 before ending the setting processing andproceeding to step 93 in FIG. 2. As a result, the shutter speed settingis adjusted to a higher speed setting by one step.

In step S122, the arithmetic operation circuit 101 makes a decision asto whether or not the shutter speed is to be adjusted to a lower speedsetting. The arithmetic operation circuit 101 makes an affirmativedecision in step S122 if the operation signal from the shutter speedsetting operation member 107 indicates a lower speed setting to proceedto step S123. However, it makes a negative decision in step S122 if theoperation signal does not indicate a lower speed setting to end thesetting processing and proceed to step S3 in FIG. 2.

In step S123, the arithmetic operation circuit 101 makes a decision asto whether or not the pre-adjustment TVs setting is −5. The arithmeticoperation circuit 101 makes an affirmative decision in step S123 ifTVs=−5 (the shutter speed setting is 30 sec) to end the settingprocessing and proceed to step S3 in FIG. 2. In this case, the shutterspeed setting is at the lower limit of the shutter speed setting rangeand thus, the setting processing ends without further lowering theshutter speed. If, on the other hand, TVs≠−5, the arithmetic operationcircuit 101 makes a negative decision in step S123 to proceed to stepS124. In step S124, the arithmetic operation circuit 101 decrements theshutter speed setting TVs by 1 before ending the setting processing andproceed to step S3 in FIG. 2. As a result, the shutter speed setting isadjusted to a lower speed setting by one step.

In step S125, the arithmetic operation circuit 101 makes a decision asto whether or not the S mode is currently selected. The arithmeticoperation circuit 101 makes an affirmative in step S125 if M=1 to endthe setting processing and proceed to step S3 in FIG. 2. In this case,no setting operation for the aperture value is executed. The arithmeticoperation circuit 101 makes a negative decision in step S125 if M≠1 toproceed to step S126.

In step S126, the arithmetic operation circuit 101 makes a decision asto whether or not an aperture value change operation has been performed.The arithmetic operation circuit 101 makes an affirmative decision instep S126 if an operation signal has been input from the aperture valuesetting operation member 108 to proceed to step S127, whereas it makes anegative decision in step S126 if no operation signal has been inputfrom the aperture value setting operation member 108 to end the settingprocessing and proceed to step S3 in FIG. 2.

In step S127, the arithmetic operation circuit 101 makes a decision asto whether or not the aperture value is to be adjusted toward amore opensetting. The arithmetic operation circuit 101 makes an affirmativedecision in step S127 if the operation signal from the aperture valuesetting operation member 108 indicates an adjustment to the open side toproceed to step S128, whereas it makes a negative decision in step S127if the operation signal does not indicate an adjustment toward a moreopen setting to proceed to step S130.

In step S128, the arithmetic operation circuit 101 makes a decision asto whether or not the pre-adjustment AVs setting is 3. The arithmeticoperation circuit 101 makes an affirmative decision in step S128 ifAVs=3 (the aperture value setting is F2.8) to end the setting processingand proceed to step S3 in FIG. 2. In this case, the aperture value isset at the upper limit of the aperture value setting range and thus, thesetting processing ends without further adjustment. If, on the otherhand, AVs 13, the arithmetic operation circuit 101 makes a negativedecision in step S128 to proceed to step S129. In step S129, thearithmetic operation circuit 101 decrements the aperture value settingAVs by 1 before ending the setting processing and proceeding to step S3in FIG. 2. As a result, the aperture value setting is adjusted towardthe open side by one step.

In step S130, the arithmetic operation circuit 101 makes a decision asto whether or not the aperture value is to be adjusted for a smalleropening. The arithmetic operation circuit 101 makes an affirmativedecision in step S130 if the operation signal from the aperture valuesetting operation member 108 indicates a smaller opening to proceed tostep S131. However, it makes a negative decision in step S130 if theoperation signal does not indicate a smaller opening to end the settingprocessing and proceed to step S3 in FIG. 2.

In step S131, the arithmetic operation circuit 101 makes a decision asto whether or not the pre-adjustment AVs setting is 9. The arithmeticoperation circuit 101 makes an affirmative decision in step S131 ifAVs=9 (the aperture value setting is F22) to end the setting processingand proceed to step S3 in FIG. 2. In this case, the aperture value isset at the lower limit of the aperture value setting range and thus, thesetting processing ends without further adjustment. If, on the otherhand, AVs≠9, the arithmetic operation circuit 101 makes a negativedecision in step S131 to proceed to step S132. In step S132, thearithmetic operation circuit 101 increments the aperture value settingAVs by 1 before ending the setting processing and proceeding to step S3in FIG. 2. As a result, the aperture value setting is adjusted towardthe closed side by one step.

The communication processing executed to allow the camera body 1 and theexternal flash unit 11 to engage in communication with each other is nowexplained in detail in reference to the flowchart presented in FIG. 6.In step S141 in FIG. 6, the arithmetic operation circuit 101 resets atime count TM to 0 and then the operation proceeds to step S142.

In step S142, the arithmetic operation circuit 101 starts a time countTM and then the operation proceeds to step S143. In step S143, thearithmetic operation circuit 101 makes a decision as to whether or notcommunication with the controller 201 has been achieved. The decision asto whether or not communication has been achieved is made by executing aspecific protocol check. The arithmetic operation circuit 101 makes anaffirmative decision in step S143 if communication has been achieved toproceed to step S144. If, on the other hand, communication has not beenachieved, the arithmetic operation circuit 101 makes a negative decisionin step S143 to proceed to step S148.

In step S144, the arithmetic operation circuit 101 transmits signalsindicating the setting of the flag P and the main flash quantity h tothe controller 201 before proceeding to step S145. In step S145, thearithmetic operation circuit 101 receives signals indicating a maximumflash quantity hmax and a minimum flash quantity hmin of the externalflash unit 11 and the setting of a flag F from the controller 201, andthen the operation proceeds to step S146. The flag F is set to 1 when acharge of the external flash unit 11 is completed and is set to 0 whenthe charges not completed.

In step S146, the arithmetic operation circuit 101 sets a flag R to 1before proceeding to step S147. The flag R is set to 1 whencommunication is achieved and is set to 0 if successful communication isnot achieved.

In step S147, the arithmetic operation circuit 101 stops the time countTM, ends the communication processing and proceeds to step S5 in FIG. 2.In step S148 to which the operation proceeds after making a negativedecision in step S143 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not TM≧T1 is true withregard to the time count TM and a predetermined length of time T1. Thepredetermined length of time T1 is the sum of the length of timerequired for the protocol check and a slight time margin. The arithmeticoperation circuit 101 makes an affirmative decision in step S148 ifTM≧T1 is true, to proceed to step S149, whereas it makes a negativedecision in step S148 if TM≧T1 is not true, to return to step S143. Theoperation proceeds to step S149 when the external flash unit 11 with thecommunication function is not mounted, whereas the operation returns tostep S143 if the protocol check is still in progress. In step S149, thearithmetic operation circuit 101 sets the flag R to 0 before proceedingto step S147.

The exposure calculation processing A is now explained in detail inreference to the flowchart presented in FIGS. 7 and 8. In step S161 inFIG. 7, the arithmetic operation circuit 101 executes an arithmeticoperation to calculate EV=BV+SVs before proceeding to step S162. EVrepresents the exposure value. The image-capturing sensitivity settingSVs is the image-capturing sensitivity having been set through anoperation of the sensitivity setting operation member 110. The subjectbrightness BV is indicated with the value obtained through theprocessing executed in step S7 or step S24 or S 52 to be explainedlater.

In step S162, the arithmetic operation circuit 101 makes a decision asto whether or not the program automatic exposure mode (P mode) iscurrently selected for the exposure mode. The arithmetic operationcircuit 101 makes an affirmative decision in step S162 if M=0 (P mode)to proceed to step S163, whereas it makes a negative decision in stepS162 if M≠0 to proceed to step S191 in FIG. 8.

The processing in steps S163 through S176 in FIG. 7 is executed when thecamera is set in the P mode. In step S163, the arithmetic operationcircuit 101 makes a decision as to whether or not the exposure value EVis greater than 22. The arithmetic operation circuit 101 makes anaffirmative decision in step S163 if EV>22 is true, to proceed to stepS164, whereas it makes a negative decision in step S163 if EV>22 is nottrue, to proceed to step S166.

In step S164, the arithmetic operation circuit 101 sets a controlshutter speed TVc to 13 ( 1/8000 sec) before proceeding to step S165. Instep S165, the arithmetic operation circuit 101 sets a control aperturevalue AVc to 9 (F22 (minimum aperture)) before proceeding to step S177.

In step S166, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure value EV is equal to or greater than 20.The arithmetic operation circuit 101 makes an affirmative decision instep S166 if EV≧20 is true, to proceed to step S167, whereas it makes anegative decision in step S166 if EV≧20 is not true, to proceed to stepS169.

In step S167, the arithmetic operation circuit 101 sets the controlaperture value AVc to 9 (F22 (minimum aperture)) before proceeding tostep S168. In step S168, the arithmetic operation circuit 101 sets avalue obtained by subtracting 9 (the minimum aperture) from the exposurevalue EV for the control shutter speed TVc, and then the operationproceeds to step S177.

In step S169, the control circuit 101 makes a decision as to whether ornot the exposure value EV is equal to or greater than 8. The arithmeticoperation circuit 101 makes an affirmative decision in step S169 if EV≧8is true, to proceed to step S170, whereas it makes a negative decisionin step S169 if EV≧8 is not true, to proceed to step S172.

In step S170, the arithmetic operation circuit 101 executes anarithmetic operation to calculate AVc=EV/2−1, and then the operationproceeds to step S171. AVc represents the control aperture value. Instep S171, the arithmetic operation circuit 101 executes an arithmeticoperation to calculate TVc=EV/2+1 before proceeding to step S177. TVcrepresents the control shutter speed.

In step S172, the control circuit 101 makes a decision as to whether ornot the exposure value EV is equal to or greater than −2. The arithmeticoperation circuit 101 makes an affirmative decision in step S172 ifEV≧−2 is true, to proceed to step S173, whereas it makes a negativedecision in step S172 if EV≧−2 is not true, to proceed to step S175.

In step S173, the arithmetic operation circuit 101 sets 3 (F2.8 (maximumaperture)) for the control aperture value AVc before proceeding to stepS174. In step S174, the arithmetic operation circuit 101 sets a valueobtained by subtracting 3 (open aperture value) from the exposure valueEV for the control shutter speed TVc, and then the operation proceeds tostep S177.

In step S175, the arithmetic operation circuit 101 sets 3 (F2.8 (maximumaperture)) for the control aperture value AVc before proceeding to stepS176. In step S176, the arithmetic operation circuit 101 sets −5 (30sec) for the control shutter speed TVc before proceeding to step S177.

The processing in steps S163 through S176 is executed as indicated inthe program chart in FIG. 21, which corresponds to the operationexecuted without utilizing either of the flash units.

In step S177, the arithmetic operation circuit 101 calculates a controlaperture pulse number Pc representing the number of control aperturepulses as a function f of the number of steps (AVc−3) over which theaperture is to be adjusted, before the operation proceeds to step S178.The control aperture pulse number Pc indicates the number of detectionpulses output from the aperture position detection device 116 before theaperture becomes held at the position corresponding to the controlaperture value AVc. While the number of steps over which the aperture isto be adjusted and the aperture pulse number are in proportion to eachother, the number of aperture detection pulses output when the apertureis more open is greater and, for this reason, the aperture pulse numberis calculated as a function f of the number of steps over which theaperture is to be adjusted (AVc−3).

In step S178, the arithmetic operation circuit 101 executes anarithmetic operation to calculate the exposure deviation ΔEV asindicated in (2) below before proceeding to step S179.

ΔEV=TVc+AVc−EV  (2)

(TVc+AVc) in the expression above represents the control exposure and EVrepresents the optimal exposure.

In step S179, the arithmetic operation circuit 101 makes a decision asto whether or not the sensitivity automatic control mode flag S iscurrently set to 1 (whether or not the sensitivity automatic controlmode is currently selected). The arithmetic operation circuit 101 makesan affirmative decision in step S179 if S=1 to proceed to step S180,whereas it makes a negative decision in step S179 if S≠1 to proceed tostep S188. The operation proceeds to step S188 when the sensitivityautomatic control mode has been cleared.

In step S188, the arithmetic operation circuit 101 sets theimage-capturing sensitivity SVs for the control image-capturingsensitivity SVc and then the operation proceeds to step S189. In stepS189, the arithmetic operation circuit 101 sets 0 for a flag C beforeending the exposure calculation processing A and proceeding to step S9in FIG. 2. The flag C is set to 1 if the image-capturing sensitivity ischanged from the image-capturing sensitivity setting SVs (SVc≠SVs) andis set to 0 if the image-capturing sensitivity remains unchanged fromthe current image-capturing sensitivity setting SVs (SVc=SVs).

In step S180, the arithmetic operation circuit 101 executes anarithmetic operation to calculate SVc=SVs+6ΔEV before proceeding to stepS181. As a result, the control image-capturing sensitivity SVc is set toa value different from the value of the image-capturing sensitivitysetting SVs, so as to achieve the optimal exposure. In step S181, thearithmetic operation circuit 101 makes a decision as to whether or notSVc>9 is true. The arithmetic operation circuit 101 makes an affirmativedecision in step S181 if SVc>9 is true (if the control image-capturingsensitivity is higher than a level equivalent to ISO 1600) to proceed tostep S182, whereas it makes a negative decision in step S181 if SVc>9 isnot true, to proceed to step S183. In step S182, the arithmeticoperation circuit 101 sets 9 for the control image-capturing sensitivitySVc, and then the operation proceeds to step S185. Thus, the controlimage-capturing sensitivity is set to the value equivalent to ISO 1600,which is the upper limit of the control range.

In step S183 to which the operation proceeds after making a negativedecision in step S181 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not SVc<5 is true. Thearithmetic operation circuit 101 makes an affirmative decision in stepS183, if SVc<5 is true (if the control image-capturing sensitivity islower than a level equivalent to ISO 100) to proceed to step S184,whereas it makes a negative decision in step S183 if SVc<5 is not true,to proceed to step S185. In step S184, the arithmetic operation circuit101 sets 5 for the control sensitivity SVc and then the operationproceeds to step S185. As a result, the control sensitivity is set tothe value equivalent to ISO 100, which is the lower limit of the controlrange.

In step S185, the arithmetic operation circuit 101 makes a decision asto whether or not SVc=SVs is true. The arithmetic operation circuit 101makes a negative decision in step S185 if Svc=SVs is not true, toproceed to step S187, whereas it makes an affirmative decision in stepS185 if SVc=SVs is true, to proceed to step S186. In step 9187, thearithmetic operation circuit 101 sets 1 for the flag C before ending theexposure calculation processing A and proceeding to step S9 in FIG. 2.

In step S186, the arithmetic operation circuit 101 sets 0 for the flag Cbefore ending the exposure calculation processing A and proceeding tostep S9 in FIG. 2.

The processing in steps S191 and subsequent steps in FIG. 8 is executedwhen an exposure mode other than the P mode is selected. In step S191,the arithmetic operation circuit 101 makes a decision as to whether ornot the shutter speed priority automatic exposure mode (S mode) has beenselected for the exposure mode. The arithmetic operation circuit 101makes an affirmative decision in step S191 if M=1 (S mode) to proceed tostep S192, whereas it makes a negative decision in step S191 if M≠1 toproceed to step S198.

In step S192, the arithmetic operation circuit 101 sets the currentlyselected shutter speed TVs for the control shutter speed TVc beforeproceeding to step S193. In step S193, the arithmetic operation circuit101 sets a value obtained by subtracting the shutter speed setting TVsfrom the exposure value EV for the control aperture value AVc, and thenthe operation proceeds to step S194.

In step S194, the arithmetic operation circuit 101 makes a decision asto whether or not AVc<3 is true. The arithmetic operation circuit 101makes an affirmative decision in step S194 if AVc<3 is true (if thecontrol aperture value is smaller than F2.8) to proceed to step S195,whereas it makes a negative decision in step S194 if AVc<3 is not true,to proceed to step S196. In step S195, the arithmetic operation circuit101 sets 3 for the control aperture value AVc before proceeding to stepS177 in FIG. 7. Thus, the control aperture value is set to F2.8, whichis the lower limit of the control range.

In step S196, the arithmetic operation circuit 101 makes a decision asto whether or not AVc>9 is true. The arithmetic operation circuit 101makes an affirmative decision in step S196 if AVc>9 is true (if thecontrol aperture value is greater than F22) to proceed to step S197,whereas it makes a negative decision in step S196 if AVc>9 is not true,to proceed to step S177 in FIG. 7. In step S197, the arithmeticoperation circuit 101 sets 9 for the control aperture value AVc beforeproceeding to step S177 in FIG. 7. Thus, the control aperture value isset to F22, which is the upper limit of the control range.

In step S198, to which the operation proceeds after making a negativedecision in step S191 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not the aperture priorityautomatic exposure mode (A mode) has been selected for the exposuremode. The arithmetic operation circuit 101 makes an af firmativedecision in step S198 if M=2 (A mode) to proceed to step S199, whereasit makes a negative decision in step S198 if M≠2 to proceed to stepS205.

In step S199, the arithmetic operation circuit 101 sets the aperturevalue AVs for the control aperture value AVc before proceeding to stepS200. In step S200, the arithmetic operation circuit 101 sets a valueobtained by subtracting the aperture value setting AVs from the exposurevalue EV for the control shutter speed TVc before proceeding to stepS201.

In step S201, the arithmetic operation circuit 101 makes a decision asto whether or not TVc<−5 is true. The arithmetic operation circuit 101makes an affirmative decision in step S201 if TVc<−5 is true (if thecontrol shutter speed is lower than 30 sec) to proceed to step S202,whereas it makes a negative decision in step S201 if TVc<−5 is not true,to proceed to step S203. In step S202, the arithmetic operation circuit101 sets −5 for the control shutter speed TVc before proceeding to stepS177 in FIG. 7. Thus, the control shutter speed is set to 30 sec, whichis the lower limit of the control range.

In step S203, the arithmetic operation circuit 101 makes a decision asto whether or not TVc>13 is true. The arithmetic operation circuit 101makes an affirmative decision in step S203 if TVc>13 is true (if thecontrol shutter speed is higher than 1/8000 sec) to proceed to stepS204, whereas it makes a negative decision in step S203 if TVc>13 is nottrue, to proceed to step S177 in FIG. 7. In step S204, the arithmeticoperation circuit 101 sets 13 sec for the control shutter speed TVcbefore proceeding to step S177 in FIG. 7. Thus, the control shutterspeed is set to 1/8000 sec, which is the upper limit of the controlrange.

In step S205, to which the operation proceeds after making a negativedecision in step S198 as described above, the arithmetic operationcircuit 101 sets the shutter speed TVs for the control shutter speed TVcbefore proceeding to step S206. In step S206, the arithmetic operationcircuit 101 sets the aperture value AVs for the control aperture valueAVc before proceeding to step S177 in FIG. 7.

The display processing is now explained in detail in reference to theflowchart presented in FIG. 9. In step S211 in FIG. 9, the arithmeticoperation circuit 101 turns on a display indicating the exposure modeand the control aperture value AVc at the display device 11, and theoperation proceeds to step S212. At the display device 111, the currentexposure mode and the F value corresponding to the apex value areindicated.

In step S212, the arithmetic operation circuit 101 makes a decision asto whether or not the mode parameter M is currently set to 3. Thearithmetic operation circuit 101 makes an affirmative decision in stepS212 if M=3 (M mode) to proceed to step S215, whereas it makes anegative decision in step S212 if M≠3 (a mode other than the M mode) toproceed to step S213.

In step S213, the arithmetic operation circuit 101 makes a decision asto whether or not the mode parameter M is currently set to 1. Thearithmetic operation circuit 101 makes an affirmative decision in stepS213 if M=1 (S mode) to proceed to step S216, whereas it makes anegative decision in step S213 if M≠1 (a mode other than the S mode) toproceed to step S214.

As neither the M mode nor the S mode is currently selected, thearithmetic operation circuit 101 turns on a display indicating thecontrol shutter speed TVc at the display device 111 in step S214 beforeproceeding to step S218. At the display device 111, the shutter speedcorresponding to the apex value is indicated.

In step S215, the arithmetic operation circuit 101 issues an instructionfor the display device 111 to indicate the negative value of theexposure deviation ΔEV as the difference relative to the optimalexposure, and then the operation proceeds to step S216. As a result, theexposure deviation is indicated at the display device 111.

In step S216, the arithmetic operation circuit 101 makes a decision asto whether or not TVc=TVs is true. The arithmetic operation circuit 101makes a negative decision in step S216 if TVc=TVs is not true, toproceed to step S217, whereas it makes an affirmative decision in stepS216 if TVc=TVs is true, to proceed to step S214.

In step S217, the arithmetic operation circuit 101 engages the displaydevice 111 to flash a display of the control shutter speed TVc so as toindicate that TVc≠TVs, and then the operation proceeds to step S218. Thedisplay device 111, in turn, flashes a display of the shutter speedcorresponding to the apex value. Such a flashing display constitutes awarning.

In step S218, the arithmetic operation circuit 101 makes a decision asto whether or not the sensitivity automatic control mode flag S iscurrently set to 1. The arithmetic operation circuit 101 makes anaffirmative decision in step S218 if S=1 (the sensitivity automaticcontrol mode is currently set) to proceed to step S219, whereas it makesa negative decision in step S218 if S=0 (the sensitivity automaticcontrol mode has been cleared) to proceed to step S223.

In step S219, the arithmetic operation circuit 101 makes a decision asto whether or not the flag C is currently set to 1. The arithmeticoperation circuit 101 makes an affirmative decision in step S219 if C=1(SVc≠SVs) to proceed to step S220, whereas it makes a negative decisionin step S219 if C=0 (SVc=SVs) to proceed to step S222.

In step S220, the arithmetic operation circuit 101 brings up a flashingdisplay of characters “ISO AUTO” or an icon at the display device 111before proceeding to step S221. In step S221, the arithmetic operationcircuit 101 also brings up a display of the ISO value corresponding tothe apex value representing the control image-capturing sensitivity SVcat the display device 111 before ending the display processing in FIG. 9and proceeding to step S10 in FIG. 2.

In step S222, the arithmetic operation circuit 101 brings up a flashingdisplay of characters “ISO AUTO” or an icon at the display device 111before proceeding to step S223. In step S223, the arithmetic operationcircuit 101 brings up a further display of the ISO value correspondingto the apex value representing the image-capturing sensitivity settingSVs at the display device 111 before ending the display processing inFIG. 9 and proceeding to step S10 in FIG. 2.

The image-capturing sequence processing A is now explained in detail inreference to the flowchart presented in FIG. 10. In step S231 in FIG.10, the arithmetic operation circuit 101 outputs a command for theshutter drive circuit 114 to supply power to the magnets (not shown) atthe shutter 115 to hold the front curtain and the rear curtain. In stepS232, the arithmetic operation circuit 101 starts a purge or dischargeof unnecessary electrical charge in the data transfer path at theimage-capturing element 121 before the operation proceeds to step S233.

In step S233, the arithmetic operation circuit 101 outputs a command forthe motor drive circuit 112 to start a forward rotation of the sequencemotor 113 before the operation proceeds to step S234. In response, themirror (not shown) starts to rise and an aperture setting operationstarts. In step S234, the arithmetic operation circuit 101 counts thedetection pulse signals input from the aperture position detectiondevice 116 and then the operation proceeds to step S235.

In step S235, the arithmetic operation circuit 101 makes a decision asto the count value Pk and the control aperture pulse number Pc achieve arelationship expressed as Pk≧Pc. The arithmetic operation circuit 101makes an affirmative decision in step S235 if Pk≧Pc is true, to proceedto step S236, whereas it makes a negative decision in step S235 if Pk≧Pcis not true. After making a negative decision in step S235, theoperation returns to step S234 to continuously execute the aperturesetting operation and then repeatedly execute the decision-makingprocessing in step S235.

In step S236, the arithmetic operation circuit 101 outputs a command forthe aperture holding device 117 to hold the aperture before proceedingto step S237. In step S237, the arithmetic operation circuit 101 makes adecision as to whether or not the mirror ascent has ended. Thearithmetic operation circuit 101 makes an affirmative decision in stepS237 if an ON signal has been input from the sequence switch SW4 toproceed to step S238, whereas it makes a negative decision in step S237if no ON signal has been input from the sequence switch SW4. Aftermaking a negative decision in step S237, the mirror is allowed tocontinuously rise and then the decision-making processing in step S237is repeatedly executed.

In step S238, the arithmetic operation circuit 101 outputs a command forthe motor drive circuit 112 to stop the forward rotation of the sequencemotor 113 before the operation proceeds to step S239. It is to be notedthat the sequence drive device (not shown) is structured so that theaperture becomes completely held by the aperture holding device 117before the mirror ascent ends.

In step S239, the arithmetic operation circuit 101 ends the discharge ofunnecessary electrical charge at the image-capturing element 121 andthen the operation proceeds to step S240. In step S240, the arithmeticoperation circuit 101 outputs a command for the shutter drive circuit114 to stop the power supply to the magnet (not shown) at the shutter115 to release to hold on the front curtain before proceeding to stepS241. In response, the front curtain at the shutter starts its run.

In step S241, the arithmetic operation circuit 101 makes a decision asto whether or not the X contact point switch SW5 has entered an ONstate. The arithmetic operation circuit 101 makes an affirmativedecision in step S241 if an ON signal has been input from the X contactpoint switch SW5 to proceed to step S242, whereas it makes a negativedecision in step S241 if no ON signal has been input from the X contactpoint switch SW5 to repeatedly execute the decision-making processing.

In step S242, the arithmetic operation circuit 101 resets the time countTM to 0 before the operation proceeds to step S243. In step S243, thearithmetic operation circuit 101 starts a time count TM beforeproceeding to step S244. In step S244, the arithmetic operation circuit101 starts a charge storage at the image-capturing element 121 beforethe operation proceeds to step S245.

In step S245, the arithmetic operation circuit 101 makes a decision asto whether or not a length of time corresponding to the control shutterspeed TVc has elapsed since the start of the time count. The arithmeticoperation circuit 101 makes an affirmative decision in step S245 ifTM≧2^(−TVc) is true, to proceed to step S246, whereas it makes anegative decision in step S245 if TM≧2^(−TVc) is not true, to repeatedlyexecute the same decision-making processing.

In step S246, the arithmetic operation circuit 101 ends the chargestorage at the image-capturing element 121 before proceeding to stepS247. In step S247, the arithmetic operation circuit 101 stops the timecount TM and then the operation proceeds to step S248.

In step S248, the arithmetic operation circuit 101 outputs a command forthe shutter drive circuit 114 to stop the power supply to the magnet atthe shutter 115 to release to hold on the rear curtain, before theoperation proceeds to step S249. In response, the rear curtain at theshutter starts its run and, as a result, the image-capturing element 121becomes shielded from the subject light. Thus, the exposure iscontrolled in correspondence to the control shutter speed TVc.

In step S249, the arithmetic operation circuit 101 outputs a command forthe motor drive circuit 112 to start a reverse rotation of the sequencemotor 113 and then the operation proceeds to step S250. As a result, themirror (not shown) starts descending and an aperture open reset starts.In step S250, the arithmetic operation circuit 101 inserts await periodof a predetermined length before proceeding to step S251. This waitperiod is set to the length of time required for the rear curtain tocompletely shield the image-capturing area at the image-capturingelement 121 from light and complete its run.

In step S251, the arithmetic operation circuit 101 starts a read of thestored electrical charges from the image-capturing element 121, and thenthe operation proceeds to step S252. As a result, the image signals readfrom the image-capturing element 121 are converted to digital data atthe A/D conversion circuit 122 and the data resulting from theconversion are provided to the image processing circuit 123.

In step S252, the arithmetic operation circuit 101 issues an instructionfor the image processing circuit 123 to execute the image processingbefore proceeding to step S253. In step S253, the arithmetic operationcircuit 101 issues an instruction for the image processing circuit 123to execute image compression processing and then the operation proceedsto step S254. In step S254, the arithmetic operation circuit 101 recordsthe compressed image data into the recording medium 126 and then theoperation proceeds to step S255.

In step S255, the arithmetic operation circuit 101 makes a decision asto whether or not the mirror descent has ended. The arithmetic operationcircuit 101 makes an affirmative decision in step S255 if an ON signalhas been input from the sequence switch SW4 to proceed to step S256,whereas it makes a negative decision in step S255 if no ON signal hasbeen input from the sequence switch SW4 to repeat the decision-makingprocessing.

In step S256, the arithmetic operation circuit 101 outputs a command forthe motor drive circuit 112 to stop the reverse rotation of the sequencemotor 113, thereby ending the processing for the image-capturingsequence A in FIG. 10 to return to step S2 in FIG. 2.

(When the Internal Flash Unit is Utilized)

The processing executed in case 2 is now explained in reference to theflowchart presented in FIG. 3. In step S21 in FIG. 3, the arithmeticoperation circuit 101 makes a decision as to whether or not the chargeflag J is currently set to 0. The arithmetic operation circuit 101 makesan affirmative decision in step S21 if J=0 (the charge at the chargecircuit in the internal flash unit light emission circuit 102 (seeFIG. 1) has not been completed) to proceed to step S22, whereas it makesa negative decision in step S21 if J=1 to proceed to step S23.

In step S22, the arithmetic operation circuit 101 issues an instructionfor the internal flash unit light emission circuit 102 to start a chargebefore proceeding to step S23. Since the processing executed in stepsS23 and S 24 is identical to the processing in steps S6 and S 7explained earlier, its explanation is omitted.

In step S25, the arithmetic operation circuit 101 executes the exposurecalculation processing B and then the operation proceeds to step S26.The exposure calculation processing B is to be explained in detaillater. In step S26, the arithmetic operation circuit 101 executesdisplay processing for the display device 111 before proceeding to stepS27. The display processing has been explained in detail earlier.

Since the processing executed in steps S27 through S30 is identical tothe processing executed in steps S10 through S13 explained earlier, itsexplanation is omitted.

In step S31 in FIG. 3, the arithmetic operation circuit 101 makes adecision as to whether or not the charge flag J is currently set to 0.The arithmetic operation circuit 101 makes an affirmative decision instep S31 if J=0 (the charge at the charge circuit in the internal flashunit light emission circuit 102 (see FIG. 1) has not been completed) toproceed to step S32, whereas it makes a negative decision in step S31 ifJ=1 to proceed to step S34.

In step S32, the arithmetic operation circuit 101 makes a decision as towhether or not the charge has been completed. The arithmetic operationcircuit 101 makes an affirmative decision in step S32 if a completesignal has been input from the internal flash unit light emissioncircuit 102 to proceed to step S33, whereas the operation returns tostep S2 in FIG. 2 if no complete signal has been input. When theoperation returns to step S2 instead of proceeding to step S35 toexecute shutter release decision-making processing, the camera is in ashutter release locked state.

In step S33, the arithmetic operation circuit 101 sets 1 for the chargeflag J and then the operation proceeds to step S34. In step S34, thearithmetic operation circuit 101 outputs a command for the displaydevice 111 to bring up a display indicating the completion of thecharge, and then the operation proceeds to step S35. At this time, thedisplay device may indicate the charge completion by, for instance,lighting an icon of a thunderbolt in the viewfinder (not shown).

In step S35, the arithmetic operation circuit makes a decision as towhether or not a full press operation (shutter release) has beenperformed. The arithmetic operation circuit 101 makes an affirmativedecision in step S35 if an operation signal has been input from the fullpress switch SW3 to proceed to step S36, whereas it makes a negativedecision in step S35 if no operation signal has been input from the fullpress switch SW3 to return to step S2 in FIG. 2.

In step S36, the arithmetic operation circuit 101 executes theimage-capturing sequence processing B before proceeding to step S37. Theimage-capturing sequence processing B is to be explained in detaillater. In step S37, the arithmetic operation circuit 101 makes adecision with regard to a flag K. The flag K is set to 1 if the controlimage-capturing sensitivity SVc and the image-capturing sensitivitysetting SVs are different from each other during the image-capturingsequence and is set to 0 if they match. The arithmetic operation circuit101 makes an affirmative decision in step S37 if K=1 to proceed to stepS38, whereas it makes a negative decision in step S37 if K=0 to proceedto step S39.

In step S38, to which the operation proceeds after a photographingoperation has been performed at a sensitivity level different from theimage-capturing sensitivity setting SVs, the arithmetic operationcircuit 101 outputs a command for the display device 111 to bring up aflashing display of the characters “ISO AUTO” or an icon, and then theoperation proceeds to step S39. In step S39, the arithmetic operationcircuit 101 makes a decision with regard to a flag FU. The flag FU isset to 1 in the event of under-exposure caused by an insufficient flashquantity even after the image-capturing sensitivity setting SVs isadjusted, and is set to 0 if under-exposure does not manifest. Thearithmetic operation circuit 101 makes an affirmative decision in stepS39 if FU=1 to proceed to step S40, whereas it makes a negative decisionin step S39 if FU=0 to proceed to step S41.

In step S40, the arithmetic operation circuit 101 outputs a command forthe display device 111 to display a warning indicating an insufficientflash quantity (under-exposure) before proceeding to step S43. At thistime, the display device may flash, for instance, a thunderbolt icon andthe characters “UNDER”. In step S43, the arithmetic operation circuit101 sets 0 for the charge flag J before returning to step S2 in FIG. 2.The sequence of the photographing processing thus ends.

In step S41, the arithmetic operation circuit 101 makes a decision withregard to a flag FO. The flag FO is set to 1 in the event ofover-exposure caused by an excessive flash quantity, even after theimage-capturing sensitivity setting SVs is adjusted, and is set to 0 ifover-exposure does not manifest. The arithmetic operation circuit 101makes an affirmative decision in step S41 if FO=1 to proceed to stepS42, whereas it makes a negative decision in step S41 if FO=0 to proceedto step S43.

In step S42, the arithmetic operation circuit 101 outputs a command forthe display device 111 to display a warning indicating an excessiveflash quantity (over-exposure) before proceeding to step S43. At thistime, the display device may flash, for instance, a thunderbolt icon andthe characters “OVER”.

The exposure calculation processing B executed when the flash unit isutilized is now explained in detail in reference to the flowchartpresented in FIG. 11. Since the processing executed in steps S261 andS262 is identical to the processing executed in steps S161 and S162explained earlier, its explanation is omitted.

In step S263, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure value EV is greater than 18. Thearithmetic operation circuit 101 makes an affirmative decision in stepS263 if EV>18 is true, to proceed to step S264, whereas it makes anegative decision in step S263 if EV>18 is not true, to proceed to stepS266.

In step S264, the arithmetic operation circuit 101 sets the controlshutter speed TVc to 9 ( 1/500 sec) before proceeding to step S265. Instep S265, the control circuit 101 sets the control aperture value AVcto 9 (F22 (minimum aperture)) before proceeding to step S294.

In step S266, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure value EV is equal to or greater than 12.The arithmetic operation circuit 101 makes an affirmative decision instep S266 if EV≧12 is true, to proceed to step S267, whereas it makes anegative decision in step S266 if EV≧12 is not true, to proceed to stepS269.

In step S267, the arithmetic operation circuit 101 sets the controlshutter speed Tvc to 9 ( 1/500 sec) before proceeding to step S268. Instep S268, the arithmetic operation circuit 101 sets a value obtained bysubtracting 9 ( 1/500 sec) from the exposure value EV for the controlaperture value AVc before proceeding to step S294.

In step S269, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure value EV is equal to or greater than −2.The arithmetic operation circuit 101 makes an affirmative decision instep S269 if EV≧−2 is true, to proceed to step S270, whereas it makes anegative decision in step S269 if EV≧−2 is not true, to proceed to stepS272.

In step S270, the arithmetic operation circuit 101 sets the controlaperture value AVc to 3 (F2.8 (maximum aperture)) before proceeding tostep S271. In step S271, the arithmetic operation circuit 101 sets avalue obtained by subtracting 3 (F2.8) from the exposure value EV forthe control shutter speed TVc, and then the operation proceeds to stepS294.

In step S272, the arithmetic operation circuit 101 sets the controlaperture value AVc to 3 (F2.8 (maximum aperture)) before proceeding tostep S273. In step S273, the arithmetic operation circuit 101 sets −5(30 sec) for the control shutter speed TVc and then the operationproceeds to step S294.

The processing in steps S263 through S273 is executed as indicated inthe program chart in FIG. 22 which represents the operation executedwhen the flash unit is utilized.

In step S274 to which the operation proceeds after making a negativedecision in step S262 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not the mode parameter Mis currently set to 1. The arithmetic operation circuit 101 makes anaffirmative decision in step S274 if M=1 (S mode) to proceed to stepS275, whereas it makes a negative decision in step S274 if M≠1 (a modeother than S mode) to proceed to step S283.

In step S275, the arithmetic operation circuit 101 makes a decision asto whether or not the shutter speed setting TVs is higher than 1/500sec. The arithmetic operation circuit 101 makes an affirmative decisionin step S275 if TVs>9 is true, to proceed to step S276, whereas it makesa negative decision in step S275 if TVs>9 is not true, to proceed tostep S278.

In step S276, the arithmetic operation circuit 101 sets 9 ( 1/500 sec)for the control shutter speed TVc before proceeding to step S277. Instep S278, the arithmetic operation circuit 101 sets the value of theshutter speed setting TVs into the control shutter speed TVc, and thenthe operation proceeds to step S277. In step S277, the arithmeticoperation circuit 101 sets a value obtained by subtracting the controlshutter speed TVc from the exposure value EV for the control aperturevalue AVc, and then the operation proceeds to step S279.

In step S279, the arithmetic operation circuit 101 makes a decision asto whether or not the control aperture value AVc is smaller than F2.8.The arithmetic operation circuit 101 makes an affirmative decision instep S279 if AVc<3 is true, to proceed to step S280, whereas it makes anegative decision in step S279 if AVc<3 is not true, to proceed to stepS281. In step S280, the arithmetic operation circuit 101 sets 3 (F 2.8(maximum aperture)) for the control aperture value AVc before proceedingto step S294.

In step S281, the arithmetic operation circuit 101 makes a decision asto whether or not the control aperture value AVc is larger than F22. Thearithmetic operation circuit 101 makes an affirmative decision in stepS281 if AVc>9 is true, to proceed to step S282, whereas it makes anegative decision in step S281 if AVc>9 is not true, to proceed to stepS294. In step S282, the arithmetic operation circuit 101 sets 9 (F 22(minimum aperture)) for the control aperture value AVc before proceedingto step S294.

Through the processing executed in steps S279 through S282, the aperturevalue is controlled within the range of F2.8 to F22.

In step S283 to which the operation proceeds after making a negativedecision in step S274 as described above, the arithmetic operationcircuit 101 makes a decision as to whether or not the mode parameter Mis currently set to 2. The arithmetic operation circuit 101 makes anaffirmative decision in step S283 if M=2 (A mode) to proceed to stepS284, whereas it makes a negative decision in step S283 if M≠2 (a modeother than A mode) to proceed to step S290.

In step S284, the arithmetic operation circuit 101 sets the value of theaperture value setting AVs into the control aperture value AVc beforeproceeding to step S285. In step S285, the arithmetic operation circuit101 sets a value obtained by subtracting the control aperture value AVcfrom the exposure value EV for the control shutter speed TVc and thenthe operation proceeds to step S286.

In step S286, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is higher than 1/500sec. The arithmetic operation circuit 101 makes an affirmative decisionin step S286 if TVc>9 is true, to proceed to step S287, whereas it makesa negative decision in step S286 if TVc>9 is not true, to proceed tostep S288. In step S287, the arithmetic operation circuit 101 sets 9 (1/500 sec) for the control shutter speed TVc before proceeding to stepS294.

In step S288, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is lower than 30 sec.The arithmetic operation circuit 101 makes an affirmative decision instep S288 if TVc<−5 is true, to proceed to step S289, whereas it makes anegative decision in step S288 if TVc<−5 is not true, to proceed to stepS294. In step S289, the arithmetic operation circuit 101 sets −5 (30sec) for the control shutter speed TVc before proceeding to step S294.

Through the processing executed in steps S286 through S289, the shutterspeed is controlled within the 30 sec to 1/500 sec range while the flashunit is utilized.

In step S290 to which the operation proceeds after making a negativedecision in step S283 as described above, the arithmetic operationcircuit 101 sets the value of the aperture value setting AVs into thecontrol aperture value AVc and then the operation proceeds to step S291.In step S291, the arithmetic operation circuit 101 makes a decision asto whether or not the shutter speed setting TVs is higher than 1/500sec. The arithmetic operation circuit 101 makes an affirmative decisionin step S291 if TVs>9 is true, to proceed to step S292, whereas it makesa negative decision in step S291 if TVs>9 is not true, to proceed tostep S293.

In step S292, the arithmetic operation circuit 101 sets 9 ( 1/500 sec)for the control shutter speed TVc before proceeding to step S294. Instep S293, the arithmetic operation circuit 101 the value of the shutterspeed setting TVs into the control shutter speed TVc, and then theoperation proceeds to step S294.

In step S294, the arithmetic operation circuit 101 calculates thecontrol aperture pulse number Pc representing the number of controlaperture pulses as a function f of the number of steps (AVc−3) overwhich the aperture is to be adjusted, thereby ending the exposurecalculation processing B in FIG. 11 to proceed to step S26 in FIG. 3.

The image-capturing sequence processing B is now explained in detail inreference to the flowchart presented in FIGS. 12 through 15. Since theprocessing executed in step S301 and step S302 in FIG. 12 is identicalto the processing executed in step S242 and step S243 explained earlier,its explanation is omitted. In step S303, the arithmetic operationcircuit 101 issues an instruction for the internal flash unit lightemission circuit 102 to start a preliminary light emission (pre-lightemission) before proceeding to step S304.

In step S304, the arithmetic operation circuit 101 receives atime-integrated value input from the emitted light detection device 118and detects the emitted light quantity Bhk from the light emitting unit44 based upon this time-integrated value, before proceeding to stepS305. In step S305, the arithmetic operation circuit 101 makes adecision as to whether or not the emitted light quantity Bhk from theinternal flash unit and a predetermined emitted light value Bh0 have arelationship expressed as Bhk≧Bh0. The arithmetic operation circuit 101makes an affirmative decision in step S305 if Bhk≧Bh0 is true, toproceed to step S306, whereas it makes a negative decision in step S305if Bhk≧Bh0 is not true. After making a negative decision in step S305,the operation proceeds to step S304 to repeatedly execute thedecision-making processing until the emitted light quantity Bhk becomesequal to the predetermined emitted light value Bh0.

In step S306, the arithmetic operation circuit 101 issues an instructionfor the internal flash unit light emission circuit 102 to stop thepreliminary light emission (pre-light emission) and then the operationproceeds to step S307. In step S307, the arithmetic operation unit 101stops the time count TM before proceeding to step S308.

In step S308, the arithmetic operation circuit 101 takes in thephotometric data (photometric data X(i) measured in correspondence toeach of the divided areas) having been accumulated at the photometeringdevice 103 during the time count TM (including the preliminary lightemission period) and stores them in memory before proceeding to stepS309.

In step S309, the arithmetic operation unit 101 takes in the photometricdata (photometric data Y(i) measured in correspondence to each dividedarea) having accumulated at the photometering device 103 during the timecount TM without emitting light at the internal flash unit afterobtaining the photometric data in step S308 and stores them in memorybefore proceeding to step S310.

In step S310, the arithmetic operation circuit 101 obtains throughcalculation photometric data (photometric data Z(i)=X(i)−Y(i) calculatedin correspondence to each divided area) from which the effect of theambient light component is eliminated, and then the operation proceedsto step S311. In step S311, the arithmetic operation circuit 101calculates a main emitted light quantity Bh to be achieved at theinternal flash unit at the control aperture value AVc and theimage-capturing sensitivity setting SVs by using the photometric datacorresponding to the individual areas from which the effect of theambient light component has been eliminated, and then the operationproceeds to step S312.

In step S312, the arithmetic operation circuit 101 compares the mainemitted light quantity Bh having been calculated for the internal flashunit with a maximum emitted light quantity Bhmax set in advance for theinternal flash unit to make a decision as to whether or not Bh>Bhmax istrue. The arithmetic operation circuit 101 makes an affirmative decisionin step S312 if Bh>Bhmax is true, to proceed to step S351 in FIG. 14,whereas it makes a negative decision in step S312 if Bh>Bhmax is nottrue, to proceed to step S313. The operation proceeds to step S351 ifthe image-capturing sensitivity setting SVs is too low and thesensitivity level thus needs to be adjusted to the controlimage-capturing sensitivity SVc, which is higher than theimage-capturing sensitivity setting SVs.

In step S313, the arithmetic operation circuit 101 compares the mainemitted light quantity Bh having been calculated for the internal flashunit with a minimum emitted light quantity Bhmin set in advance for theinternal flash unit to make a decision as to whether or not Bh<Bhmin istrue. The arithmetic operation circuit 101 makes an affirmative decisionin step S313 if Bh<Bhmin is true, to proceed to step S371 in FIG. 15,whereas it makes a negative decision in step S313 if Bh<Bhmin is nottrue, to proceed to step S314. The operation proceeds to step S371 ifthe image-capturing sensitivity setting SVs is too high and thesensitivity level thus needs to be adjusted to the controlimage-capturing sensitivity SVc which is lower than the image-capturingsensitivity setting SVs.

In step S314, the arithmetic operation circuit 101 sets 0 for the flagK, the flag FU and the flag FO before proceeding to step S315. Since theprocessing executed in steps S315 through S317 is identical to theprocessing executed in steps S231 through S233 explained earlier, itsexplanation is omitted. Once the processing in step S317 is completed,the arithmetic operation circuit 101 proceeds to step S321 in FIG. 13.

Since the processing executed in steps S321 through S330 in FIG. 13 isidentical to the processing executed in steps S234 through S243explained earlier, its explanation is omitted.

In step S331, the arithmetic operation circuit 101 issues an instructionfor the internal flash unit light emission circuit 102 to start a mainlight emission, and then the operation proceeds to step S332. In stepS332, the arithmetic operation circuit 101 starts charge storage at theimage-capturing element 121 before proceeding to step S333.

Since the processing executed in step S333 through S335 is identical tothe processing executed in steps S304 through S306 explained earlier,its explanation is omitted. However, in this case, the emitted lightquantity Bhk from the light emitting unit 44 having been detected iscompared with the emitted light quantity Bh having been calculated instep S311 and the main light emission is stopped if Bhk≧Bh is true.

Since the processing executed in steps S336 through S347 is identical tothe processing executed in steps S245 through S256 explained earlier,its explanation is omitted. Upon completing the image-capturing sequenceprocessing B in FIG. 13, the arithmetic operation circuit 101 proceedsto step S37 in FIG. 3.

In step S351 in FIG. 14 to which the operation proceeds after making anaffirmative decision in step S312 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not thesensitivity automatic control mode flag S is currently set to 1. Thearithmetic operation circuit 101 makes an affirmative decision in stepS351 if S=1 (the sensitivity automatic control mode is currently set) toproceed to step S352, whereas it makes a negative decision in step S351if S=0 (the sensitivity automatic control mode has been cleared) toproceed to step S362.

In step S352, the arithmetic operation circuit 101 calculates thecontrol image-capturing sensitivity SVc as indicated in (3) below, andthen the operation proceeds to step S353.

SVc=SVs+log₂(Bh/Bhmax)  (3)

Expression (3) above has been formulated based upon the concept that theoptimal exposure is achieved by controlling the flash quantity from theflash unit in inverse proportion to an increase in the image-capturingsensitivity (ISO equivalent).

In step S353, the arithmetic operation circuit 101 sets the emittedlight quantity Bh of the internal flash unit equal to the maximumemitted light value Bhmax before proceeding to step S354. In step S354,the arithmetic operation circuit 101 makes a decision as to whether ornot SVc>9 is true. The arithmetic operation circuit 101 makes anaffirmative decision in step S354 if SVc>9 is true (if the controlimage-capturing sensitivity is higher than the level equivalent to ISO1600) to proceed to step S355, whereas it makes a negative decision instep S354 if SVc>9 is not true, to proceed to step S358.

The operation proceeds to step S355 if the control image-capturingsensitivity SVc is beyond its setting range. In step S355, thearithmetic operation circuit 101 sets 9 for the control image-capturingsensitivity SVc, and then the operation proceeds to step S356. As aresult, the control image-capturing sensitivity is set to the levelequivalent to ISO 1600, which is the upper limit of the control range.In step S356, the arithmetic operation circuit 101 sets 1 for the flagFU and 0 for the flag FO before proceeding to step S357.

The operation proceeds step S358 if the control image-capturingsensitivity SVc is within the setting range. In step S358, thearithmetic operation circuit 101 sets 0 for both the flag FU and theflag FO before proceeding to step S357.

In step S357, the arithmetic operation circuit 101 compares the controlimage-capturing sensitivity SVc with the image-capturing sensitivitysetting SVs to determine whether or not SVc=SVs is true. The arithmeticoperation circuit 101 makes an affirmative decision in step S357 ifSVc=SVs is true, to proceed to step S359, whereas it makes a negativedecision in step S357 if SVc=SVs is not true, to proceed to step S360.

In step S359, the arithmetic operation circuit 101 sets 0 for the flagK, and then the operation proceeds to step S315 in FIG. 12. In stepS360, the arithmetic operation circuit 101 sets 1 for the flag K, andthen the operation proceeds to step S361.

In step S361, the arithmetic operation circuit 101 executes the exposurecalculation processing BB, and then the operation proceeds to step S315in FIG. 12. The exposure calculation processing BB is to be described indetail later.

In step S362 to which the operation proceeds after making a negativedecision in step S351 as described above, the arithmetic operationcircuit 101 sets 0 for the flag K, 1 for the flag FU and 0 for the flagFO and then the operation proceeds to step S315 in FIG. 12. In thissituation, the sensitivity automatic control mode is not in effect andthus the arithmetic operation circuit simply sets the flags beforeproceeding to step S315.

In step S371 in FIG. 15 to which the operation proceeds after making anaffirmative decision in step S313 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not thesensitivity automatic control mode flag S is currently set to 1. Thearithmetic operation circuit 101 makes an affirmative decision in stepS371 if S=1 (the sensitivity automatic control mode is currently set) toproceed to step S372, whereas it makes a negative decision in step S371if S=0 (the sensitivity automatic control mode has been cleared) toproceed to step S382.

In step S372, the arithmetic operation circuit 101 calculates thecontrol image-capturing sensitivity SVc as indicated in (4) below, andthen the operation proceeds to step S373.

SVc=SVs−log₂(Bhmin/Bh)  (4)

Expression (4) above has been formulated based upon the concept that theoptimal exposure is achieved by controlling the flash quantity from theflash unit in inverse proportion to a decrease in the image-capturingsensitivity (ISO equivalent).

In step S373, the arithmetic operation circuit 101 sets the emittedlight quantity Bh of the internal flash unit equal to the minimumemitted light value Bhmin before proceeding to step S374. In step S374,the arithmetic operation circuit 101 makes a decision as to whether ornot SVc<5 is true. The arithmetic operation circuit 101 makes anaffirmative decision in step S374 if SVc<5 is true (if the controlimage-capturing sensitivity is lower than the level equivalent to ISO100) to proceed to step S375, whereas it makes a negative decision instep S374 if SVc<5 is not true, to proceed to step S378.

The operation proceeds to step S375 if the control image-capturingsensitivity SVc is below its setting range. In step S375, the arithmeticoperation circuit 101 sets 5 for the control image-capturing sensitivitySVc, and then the operation proceeds to step S376. As a result, thecontrol image-capturing sensitivity is set to the level equivalent toISO 100, which is the lower limit of the control range. In step S376,the arithmetic operation circuit 101 sets the flag FU to 0 and 1 for theflag FO before proceeding to step S377.

The operation proceeds step S378 if the control image-capturingsensitivity SVc is within the setting range. In step S378, thearithmetic operation circuit 101 sets 0 for both the flag FU and theflag FO before proceeding to step S377.

In step S377, the arithmetic operation circuit 101 compares the controlimage-capturing sensitivity SVc with the image-capturing sensitivitysetting SVs to determine whether or not SVc=SVs is true. The arithmeticoperation circuit 101 makes an affirmative decision in step S377 ifSVc=SVs is true, to proceed to step S379, whereas it makes a negativedecision in step S377 if SVc=SVs is not true, to proceed to step S380.

In step S379, the arithmetic operation circuit 101 sets 0 for the flagK, and then the operation proceeds to step S315 in FIG. 12. In stepS380, the arithmetic operation circuit 101 sets 1 for the flag K, andthen the operation proceeds to step S381.

In step S381, the arithmetic operation circuit 101 executes the exposurecalculation processing BB, and then the operation proceeds to step S315in FIG. 12. The exposure calculation processing BB is to be described indetail later.

In step S382 to which the operation proceeds after making a negativedecision in step S371 as described above, the arithmetic operationcircuit 101 sets 0 for the flag K, 0 for the flag FU and 1 for the flagFO and then the operation proceeds to step S315 in FIG. 12. In thissituation, the sensitivity automatic control mode is not in effect andthus the arithmetic operation circuit simply sets the flags beforeproceeding to step S315.

(when the External Flash Unit is Utilized)

The processing executed in case 3 is now explained in reference to theflowchart presented in FIG. 4. Since the processing executed in step S51through S58 in FIG. 4 is identical to the processing executed in stepsS23 through S30 explained earlier, its explanation is omitted.

In step S59, the arithmetic operation circuit 101 makes a decision as towhether or not the value indicated by the flag F having been receivedfrom the external flash unit 11 through the communication processingexecuted as described earlier is 1. The arithmetic operation circuit 101makes an affirmative decision in step S59 if F=1 (the charge has beencompleted) to proceed to step S60, whereas it makes a negative decisionin step S59 if F≠1 (the charge has not been completed) to proceed tostep S61.

In step S60, the arithmetic operation circuit 101 outputs a command forthe display device 111 to bring up a display indicating the completionof the charge, and then the operation proceeds to step S61. At thistime, the display device may indicate the charge completion by lightinga thunderbolt icon in the viewfinder (not shown).

Since the processing executed in steps S61 through S68 is identical tothe processing executed in steps S35 through S42 explained earlier, itsexplanation is omitted. However, in this case, the image-capturingsequence processing C instead of the image-capturing sequence processingB is executed. In addition, after executing the processing step S66 orstep S68 or after making a negative decision in step S67, the operationreturns to step S2 in FIG. 2.

The image-capturing sequence processing C is now explained in detail inreference to the flowchart presented in FIGS. 16 through 19. Since theprocessing executed in steps S391 and S 392 in FIG. 16 is identical tothe processing executed in steps S242 and S 243 explained earlier, itsexplanation is omitted. In step S393, the arithmetic operation circuit101 sets 1 for the flag P before proceeding to step S394. In step S394,the arithmetic operation circuit 101 executes the communicationprocessing to communicate with the controller 201 of the external flashunit 11 as described earlier, and then the operation proceeds to stepS395. As the controller 201 at the external flash unit 11 receives flagP=1 through the communication, the light emission circuit 202 engagesthe light emitting unit 11 a to execute a preliminary light emissionwith a small output.

In step S395, the arithmetic operation circuit 101 makes a decision asto whether or not the time count TM is equal to or greater than apredetermined length of time Tpre set for the preliminary light emissionThe arithmetic operation circuit 101 makes an affirmative decision instep S395 if TM≧Tpre is true, to proceed to step S396, whereas it makesa negative decision in step S395 if TM≧Tpre is not true, to repeatedlyexecute the decision-making processing.

In step S396, the arithmetic operation circuit 101 stops the time countTM before proceeding to step S397.

In step S397, the arithmetic operation circuit 101 takes in thephotometric data (photometric data X(i) measured in correspondence toeach of the divided areas) having been accumulated at the photometeringdevice 103 during the time count TM (including the preliminary lightemission period) and stores them in memory before proceeding to stepS398.

In step S398, the arithmetic operation unit 101 takes in the photometricdata (photometric data Y(i) measured in correspondence to each dividedarea) having been accumulated at the photometering device 103 during thetime count TM without emitting light at the external flash unit 11 afterobtaining the photometric data in step S397 and stores them in memorybefore proceeding to step S399.

In step S399, the arithmetic operation circuit 101 obtains throughcalculation photometric data (photometric data Z(i)=X(i)−Y(i) calculatedin correspondence to each divided area) from which the effect of theambient light component is eliminated, and then the operation proceedsto step S400. In step S400, the arithmetic operation circuit 101calculates a main flash quantity h to be achieved at the external flashunit 11 at the control aperture value AVc and the image-capturingsensitivity setting SVs by using the photometric data corresponding tothe individual areas from which the effect of the ambient lightcomponent has been eliminated, and then the operation proceeds to stepS401.

In step S401, the arithmetic operation circuit 101 compares the mainflash quantity h having been calculated for the external flash unit 11with a maximum flash quantity hmax of the external flash unit 11 havingbeen ascertained through the communication to make a decision as towhether or not h>hmax is true. The arithmetic operation circuit 101makes an affirmative decision in step S401 if h>hmax is true, to proceedto step S441 in FIG. 18, whereas it makes a negative decision in stepS401 if h>hmax is not true, to proceed to step S402. The operationproceeds to step S441 if the image-capturing sensitivity setting SVs istoo low and the sensitivity level thus needs to be adjusted to thecontrol image-capturing sensitivity SVc, which is higher than theimage-capturing sensitivity setting SVc.

In step S402, the arithmetic operation circuit 101 compares the mainflash quantity h having been calculated for the external flash unit 11with a minimum flash quantity hmin of the external flash unit 11 havingbeen ascertained through the communication to make a decision as towhether or not h<hmin is true. The arithmetic operation circuit 101makes an affirmative decision in step S402 if h<hmin is true, to proceedto step S461 in FIG. 19, whereas it makes a negative decision in stepS402 if h<hmin is not true, to proceed to step S403. The operationproceeds to step S461 if the image-capturing sensitivity setting SVs istoo high and the sensitivity level thus needs to be adjusted to thecontrol image-capturing sensitivity SVc, which is lower than theimage-capturing sensitivity setting SVc.

In step S403, the arithmetic operation circuit 101 sets 1 for the flagK, the flag FU and the flag FO before proceeding to step S404. Since theprocessing executed in steps S404 through S406 is identical to theprocessing executed in steps S231 through S233 explained earlier, itsexplanation is omitted. Once the processing in step S406 is completed,the arithmetic operation circuit 101 proceeds to step S411 in FIG. 17.

Since the processing executed in steps S411 through S416 in FIG. 17 isidentical to the processing executed in steps S234 through S249explained earlier, its explanation is omitted.

In step S417, the arithmetic operation circuit 101 sets 0 for the flag Pand then the operation proceeds to step S418. In step S418, thearithmetic operation circuit 101 executes communication processing tocommunicate with the controller 201 at the external flash unit 11 beforeproceeding to step S419. In this case, since the flag P is set to 0, nopreliminary light emission is executed. The controller 201 receivesinformation indicating the main flash quantity h through thecommunication processing.

Since the processing executed in steps S419 and S 420 is identical tothe processing executed in steps S240 and S 241 explained earlier, itsexplanation is omitted.

In step S421, the arithmetic operation circuit 101 outputs a signalconstituting an instruction for the light emission circuit 102 at theexternal flash unit 11 to start a main light emission and then theoperation proceeds to step S422. In response to the signal thus output,the external flash unit 11 emits light at the main flash quantity h.

Since the processing executed in steps S422 through S436 is identical tothe processing executed in steps S242 through S256 explained earlier,its explanation is omitted. Upon completing the image-capturing sequenceprocessing C in FIG. 17, the arithmetic operation circuit 101 proceedsto step S63 in FIG. 4.

In step S441 in FIG. 18 to which the operation proceeds after making anaffirmative decision in step S401 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not thesensitivity automatic control mode flag S is currently set to 1. Thearithmetic operation circuit 101 makes an affirmative decision in stepS441 if S=1 (the sensitivity automatic control mode is currently set) toproceed to step S442, whereas it makes a negative decision in step S441if S=0 (the sensitivity automatic control mode has been cleared) toproceed to step S452.

In step S442, the arithmetic operation circuit 101 calculates thecontrol image-capturing sensitivity SVc as indicated in (5) below, andthen the operation proceeds to step S443.

SVc=SVs+log₂(h/hmax)  (5)

Expression (5) above has been formulated based upon the concept that theoptimal exposure is achieved by controlling the flash quantity from theflash unit in inverse proportion to an increase in the image-capturingsensitivity (ISO equivalent).

In step S443, the arithmetic operation circuit 101 sets the flashquantity h of the external flash unit 11 equal to the maximum flashquantity value hmax before proceeding to step S444.

Since the processing executed in steps S444 through S452 is identical tothe processing executed in steps S354 through S362 explained earlier,its explanation is omitted. Upon completing the processing in step S449,step S451 or step S452, the arithmetic operation circuit 101 proceeds tostep S404 in FIG. 16.

In step S461 in FIG. 19 to which the operation proceeds after making anaffirmative decision in step S402 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not thesensitivity automatic control mode flag S is currently set to 1. Thearithmetic operation circuit 101 makes an affirmative decision in stepS461 if S=1 (the sensitivity automatic control mode is currently set) toproceed to step S462, whereas it makes a negative decision in step S461if S=0 (the sensitivity automatic control mode has been cleared) toproceed to step S472.

In step S462, the arithmetic operation circuit 101 calculates thecontrol image-capturing sensitivity SVc as indicated in (6) below, andthen the operation proceeds to step S463.

SVc=SVs−log₂(hmin/h)  (6)

Expression (6) above has been formulated based upon the concept that theoptimal exposure is achieved by controlling the flash quantity from theflash unit in inverse proportion to a decrease in the image-capturingsensitivity (ISO equivalent).

In step S463, the arithmetic operation circuit 101 sets the flashquantity h of the external flash unit 11 equal to the minimum flashquantity value hmin before proceeding to step S464.

Since the processing executed in steps S464 through S472 is identical tothe processing executed in steps S374 through S382 explained earlier,its explanation is omitted. Upon completing the processing in step S469,step S471 or step S472, the arithmetic operation circuit 101 proceeds tostep S404 in FIG. 16.

The exposure calculation processing BB is now explained in reference tothe flowchart presented in FIG. 20. The exposure calculation BB isexecuted to adjust for the change in the background exposure conditionsresulting from a change in the sensitivity adjusted in order to correctany excess or insufficiency (lack) in the flash quantity of the flashunit. In step S481 in FIG. 20, the arithmetic operation circuit 101executes an arithmetic operation to calculate EV=BV+SVc beforeproceeding to step S482. EV in the expression represents the exposurevalue. The control image-capturing sensitivity SVc is theimage-capturing sensitivity level having been adjusted to correct theexcess/insufficiency of flash quantity. The subject rightness BV assumesthe value having been obtained through the processing executed in stepS7, S 24 or S 52.

In step S482, the arithmetic operation circuit 101 sets a value obtainedby subtracting the control aperture value AVc from the exposure value EVfor the control shutter speed TVc before the operation proceeds to stepS483.

In step S483, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is higher than 1/500sec. The arithmetic operation circuit 101 makes an affirmative decisionin step S483 if TVc>9 is true, to proceed to step S484, whereas it makesa negative decision in step S483 if TVc>9 is not true, to proceed tostep S485. In step S484, the arithmetic operation circuit 101 sets 9 (1/500 sec) for the control shutter speed TVc before ending the exposurecalculation processing BB as shown in FIG. 20.

In step S485, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is lower than 30 sec.The arithmetic operation circuit 101 makes an affirmative decision instep S485 if TVc<−5 is true, to proceed to step S486, whereas it makes anegative decision in step S485 if TVc<−5 is not true, and ends theprocessing in FIG. 20.

Through the processing executed in steps S483 through S486, the shutterspeed is controlled within the 30 sec to 1/500 sec range while the flashunit is utilized.

The first embodiment described above is now summarized.

The following advantages are achieved in the electronic camera 1 capableof operating in an operation mode (image-capturing sensitivity automaticcontrol mode) in which the control aperture value AVc and/or the controlshutter speed TVc can be calculated based upon the subject rightness BVand the image-capturing sensitivity setting SVc, the controlimage-capturing sensitivity Svc is also determined through an arithmeticoperation so as to achieve optimal exposure and exposure control isimplemented by switching from the image-capturing sensitivity settingSVs to the control image-capturing sensitivity SVc.

(1) When a photographing operation is performed with the electroniccamera 1 by utilizing the internal flash unit (or the external flashunit 11), in particular, the emitted light quantity (or flash quantity)Bh (or h) to be achieved through the main light emission is calculatedbased upon the time-integrated value obtained by executing a preliminarylight emission at the flash unit, which is provided by the emitted lightquantity detection device 118. If this flash quantity value is beyondthe upper limit or below the lower limit of the flash quantity of theinternal flash unit (or the external flash unit 11), optimal exposure isachieved by switching from the image-capturing sensitivity setting SVsto the control image-capturing sensitivity SVc. As a result, even whenthe quantity of light emitted from the flash unit is excessive orinsufficient, the optimal exposure can be achieved by automaticallyadjusting the image-capturing sensitivity.(2) Since the flash quantity Bh (or h) achieved through the main lightemission is calculated by first eliminating the ambient light (ambientlight from the sun, indoor lighting or the like, other than the lightemitted from the flash unit) component, the quantity of light emittedthrough the preliminary light emission at the flash unit can beaccurately ascertained.(3) When the image-capturing sensitivity setting SVs is switched to thecontrol image-capturing sensitivity SVc as described in (1) above, theexposure calculation processing BB is executed so as to adjust for thechange in the exposure (the value determined in correspondence to theshutter speed, the aperture value and the image-capturing sensitivity)of the background resulting from the change in the sensitivity level,which is adjusted to correct the excess/insufficiency of flash quantityfrom the flash unit, by adjusting the shutter speed. Thus, even if theimage-capturing sensitivity is raised to compensate for a low brightnesslevel of the main subject at the center of the photographic field whenphotographing an image with a backlit landscape in the background in afill-in flash photographing operation, for instance, over-exposure ofthe background can be prevented since the control shutter speed TVc isrecalculated (S 482).

While an explanation is given above on an example in which the internalflash unit built into the electronic camera moves between the operatingposition and the storage position, the internal flash unit does not needto be a pop-up type flash unit. If the electronic camera includes anon-pop-up flash unit, a light emission enabled state of the internalflash unit set through an operation of an operation member (not shown)of the electronic camera corresponds to the state in which the internalflash unit in the embodiment explained above assumes the operatingposition and a light emission disabled state of the internal flash unitset through an operation of the operation member corresponds to thestate in which the internal flash unit in the embodiment assumes thestorage position.

Second Embodiment

While an adjustment for the change in the background exposure isachieved through the exposure calculation processing BB regardless ofthe exposure mode setting (the P mode, the S mode, the A mode or the Mmode) in the first embodiment, the adjustment for the change in thebackground exposure may be executed only when the camera is set in the Pmode or the A mode, instead.

FIG. 23 presents a detailed flowchart of the exposure calculationprocessing BB1. The exposure calculation BB1 is executed in place of theexposure calculation BB. The processing in FIG. 23 differs from that inFIG. 20 in that additional steps S479 and S 480 are executed. In stepS479 in FIG. 23, the arithmetic operation circuit 101 makes a decisionas to whether or not the mode parameter M it is currently set to 3. Thearithmetic operation circuit 101 makes an affirmative decision in stepS479 if M=3 (M mode) to end the exposure calculation processing BB1 inFIG. 23 and, in this case, no exposure calculation is executed (theshutter speed remains unchanged). If, on the other hand, M≠3 (a modeother than the M mode), the arithmetic operation circuit 101 makes anegative decision in step S479 to proceed to step S480.

In step S480, the arithmetic operation circuit 101 makes a decision asto whether or not the mode parameter M is set to 1. The arithmeticoperation circuit 101 makes an affirmative decision in step S480 if M=1(S mode) to end the exposure calculation processing BB1 in FIG. 23 and,in this case, no exposure calculation is executed (the shutter speedremains unchanged). If, on the other hand, M≠1 (a mode other than the Mmode), the arithmetic operation circuit 101 makes a negative decision instep S480 to proceed to step S481.

Since the processing executed in step S481 and subsequent steps to whichthe operation proceeds if the camera is set neither in the M mode northe S mode is identical to the processing executed in steps assignedwith the same step numbers in FIG. 20, its explanation is omitted.

The second embodiment described above in which an adjustment for thechange in the exposure of the background resulting from a change in thesensitivity level is achieved by adjusting the shutter speed in the Pmode and the A mode but the shutter speed remains unchanged in the Mmode and the S mode, achieves an advantage in that the value of theshutter speed setting TVs is not changed against the intention of thephotographer. It is to be noted that a change in the shutter speed issynonymous with a change in the length of the exposure time.

The shutter speed may remain unchanged only in the M mode, instead. FIG.24 presents a detailed flowchart of the exposure calculation processingBB2 executed in such an application. The processing in FIG. 24 differsfrom that in FIG. 23 in that the processing in step S480 is omitted.Through the processing in FIG. 24, an adjustment for the change in theexposure of the background resulting from a change in the sensitivitylevel is achieved by switching the shutter speed in the P mode the Amode and the S mode, but the shutter speed is not changed in the M mode.As a result, the value of the shutter speed TVs set in the M mode cannotbe changed against the intention of the photographer.

Third Embodiment

While the background exposure is adjusted by changing the shutter speedin the first embodiment and the second embodiment, the backgroundexposure may instead be adjusted by re-executing the exposurecalculation matching the current exposure mode setting. FIGS. 25 through28 present a detailed flowchart of the exposure calculation processingBB3 executed in such an application. The exposure calculation BB3 isexecuted in place of the exposure calculation BB.

In step S501 in FIG. 25, the arithmetic operation circuit 101 sets theexposure value EV into a saved exposure value MEV and the controlaperture value Avc into a saved control aperture value MAVc, beforeproceeding to step S502. In step S502, the arithmetic operation circuit101 sets a value obtained by adding the control image-capturingsensitivity SVc to the subject brightness BV as the exposure value EV,and then the operation proceeds to step S503.

In step S503, the arithmetic operation circuit 101 makes a decision asto whether or not the electronic camera is set in the P mode. Thearithmetic operation circuit 101 makes an affirmative decision in stepS503 if M=0 (program automatic exposure mode) to proceed to step S504,whereas it makes a negative decision in step S503 if M≠0 (a mode otherthan the program automatic exposure mode) to proceed to step S571 inFIG. 27.

In step S504, the arithmetic operation circuit 101 makes a decision asto whether or not the exposure value EV is greater than 12. Thearithmetic operation circuit 101 makes an affirmative decision in stepS504 if EV>12 is true, to proceed to step S505, whereas it makes anegative decision in step S504 if EV>12 is not true, to proceed to stepS541 in FIG. 26.

In step S505, the arithmetic operation circuit 101 sets the controlshutter speed TVc to 9 ( 1/500 sec) before proceeding to step S506. Instep S506, the arithmetic operation circuit 101 makes a decision as towhether or not the exposure value EV is greater than 18. The arithmeticoperation circuit 101 makes an affirmative decision in step S506 ifEV>18 is true, to proceed to step S507, whereas it makes a negativedecision in step S506 if EV>18 is not true, to proceed to step S509.

In step S507, the arithmetic operation circuit 101 sets 9 (F22) for thecontrol aperture value AVc and then the operation proceeds to step S508.In step S509, the arithmetic operation circuit 101 sets a value obtainedby subtracting 9 ( 1/500 sec) from the exposure value EV for the controlaperture value AVc before proceeding to step S508.

In step S508, the arithmetic operation circuit 101 makes a decision asto whether or not the light emitting unit 44 of the internal flash unitis at the operating position. The arithmetic operation circuit 101 makesan affirmative decision in step S508 if an ON signal has been input fromthe position detection switch SW1 to proceed to step S510, whereas itmakes a negative decision in step S508 if an OFF signal has been inputfrom the position detection switch SW1 to proceed to step S529.

In step S510, the arithmetic operation circuit 101 the main emittedlight quantity Bh of the internal flash unit into a saved main flashquantity MBh, and then the operation proceeds to step S511. In stepS511, the arithmetic operation circuit 101 sets a value obtained bymultiplying 2^((AVc-MAVc)) by Bh for the main emitted light quantity Bhof the internal flash unit, before proceeding to step S512.

In step S512, the arithmetic operation circuit 101 compares the mainemitted light quantity Bh having been calculated for the internal flashunit with a maximum emitted light quantity Bhmax set in advance for theinternal flash unit to make a decision as to whether or not Bh>Bhmax istrue. The arithmetic operation circuit 101 makes an affirmative decisionin step S512 if Bh>Bhmax is true, to proceed to step S513, whereas itmakes a negative decision in step S512 if Bh>Bhmax is not true, toproceed to step S526. The operation proceeds to step S513 when the flashquantity is insufficient.

In step S513, the arithmetic operation circuit 101 sets the emittedlight quantity Bh at the internal flash unit equal to the maximumemitted light value Bhmax before proceeding to step S514. In step S514,the arithmetic operation circuit 101 calculates the control aperturevalue AVc as indicated in (7) below and then the operation proceeds tostep S515.

AVc=MAVc+log₂(Bhmax/MBh)  (7)

In step S515, the arithmetic operation circuit 101 makes a decision asto whether or not AVc>9 is true. The arithmetic operation circuit 101makes an affirmative decision in step S515 if AVc>9 is true (if thecontrol aperture value is greater than F22) to proceed to step S516,whereas it makes a negative decision in step S515 if AVc>9 is not true,to proceed to step S519.

The operation proceeds to step S516 if the control aperture value AVc isbeyond its setting range. In step S516, the arithmetic operation circuit101 sets 9 for the control aperture value AVc before proceeding to stepS517. As a result, the control aperture value is set to F22corresponding to the minimum aperture. In step S517, the arithmeticoperation circuit 101 sets the flag FU to 0 and 1 for the flag FO beforeproceeding to step S518.

In step S519, the arithmetic operation circuit 101 makes a decision asto whether or not AVc<3 is true. The arithmetic operation circuit 101makes an affirmative decision in step S519 if AVc<3 is true (if thecontrol aperture value is smaller than F2.8) to proceed to step S520,whereas it makes a negative decision in step S519 if AVc<3 is not true,to proceed to step S518.

The operation proceeds to step S520 if the control aperture value AVc isbelow its setting range. In step S520, the arithmetic operation circuit101 sets 3 for the control aperture value AVc before proceeding to stepS521. As a result, the control aperture value is set to F2.8corresponding to the full open aperture. In step S521, the arithmeticoperation circuit 101 sets the flag FU to 1 and 0 for the flag FO beforeproceeding to step S518.

In step S518, the arithmetic operation circuit 101 sets a value obtainedby subtracting the control aperture value AVc from the exposure value EVfor the control shutter speed TVc and then the operation proceeds tostep S522

In step S522, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is higher than 1/500sec. The arithmetic operation circuit 101 makes an affirmative decisionin step S522 if TVc>9 is true, to proceed to step S523, whereas it makesa negative decision in step S522 if TVc>9 is not true, to proceed tostep S524. In step S523, the arithmetic operation circuit 101 sets 9 (1/500 sec) for the control shutter speed TVc before ending the exposurecalculation processing BB3 in FIG. 25.

In step S524, the arithmetic operation circuit 101 makes a decision asto whether or not the control shutter speed TVc is lower than 30 sec.The arithmetic operation circuit 101 makes an affirmative decision instep S524 if TVc<−5 is true, to proceed to step S525, whereas it makes anegative decision in step S524 if TVc<−5 is not true, and ends theexposure calculation processing BB3 in FIG. 25. In step S525, thearithmetic operation circuit 101 sets −5 (30 sec) for the controlshutter speed TVc before ending the exposure calculation processing BB3.

Through the processing executed in steps S522 through S525, the shutterspeed is controlled within the 30 sec to 1/500 sec range while the flashunit is utilized.

In step S526, to which the operation proceeds after making a negativedecision in step S512 as described above, the arithmetic operationcircuit 101 compares the main emitted light quantity Bh having beencalculated for the internal flash unit with a minimum emitted lightquantity Bhmin set in advance for the internal flash unit to make adecision as to whether or not Bh<Bhmin is true. The arithmetic operationcircuit 101 makes an affirmative decision in step S526 if Bh<Bhmin istrue, to proceed to step S527, whereas it makes a negative decision instep S526 if Bh<Bhmin is not true, to end the exposure calculationprocessing BB3 in FIG. 25. The operation proceeds to step S527 if theflash quantity is excessive.

In step S527, the arithmetic operation circuit 101 sets the emittedlight quantity Bh at the internal flash unit equal to the minimumemitted light value Bhmin, and then the operation proceeds to step S528.In step S528, the arithmetic operation circuit 101 calculates thecontrol aperture value AVc as indicated in (8) below before proceedingto step S515.

AVc=MAVc+log₂(Bhmin/MBh)  (8)

In step S529, to which the operation proceeds after making a negativedecision in step S508 as described above, the arithmetic operationcircuit 101 sets the main flash quantity h of the external flash unit 11into a saved main flash quantity Mh, and then the operation proceeds tostep S530. In step S530, the arithmetic operation circuit 101 sets avalue obtained by multiplying 2^((AVc-MAVc)) by h for the main flashquantity h of the external flash unit 11 before proceeding to step S531.

In step S531, the arithmetic operation circuit 101 compares the mainflash quantity h having been calculated for the external flash unit 11with a maximum flash quantity hmax of the external flash unit 11 havingbeen ascertained through the communication to make a decision as towhether or not h>hmax is true. The arithmetic operation circuit 101makes an affirmative decision in step S531 if h>hmax is true, to proceedto step S532, whereas it makes a negative decision in step S531 ifh>hmax is not true, to proceed to step S534. The operation proceeds tostep S532 if the flash quantity is insufficient.

In step S532, the arithmetic operation circuit 101 sets the flashquantity h to be achieved at the external flash unit 11 equal to themaximum flash quantity value hmax, and then the operation proceeds tostep S533. In step S533, the arithmetic operation circuit 101 calculatesthe control aperture value AVc as indicated in (9) below beforeproceeding to step S515.

AVc=MAVc+log₂(hmax/Mh)  (9)

In step S534, to which the operation proceeds after making a negativedecision in step S531 as described above, the arithmetic operationcircuit 101 compares the main flash quantity h having been calculatedfor the external flash unit 11 with a minimum flash quantity hmin of theexternal flash unit 11 having been ascertained through the communicationto make a decision as to whether or not h<hmin is true. The arithmeticoperation circuit 101 makes an affirmative decision in step S534 ifh<hmin is true, to proceed to step S535, whereas it makes a negativedecision in step S534 if h<hmin is not true, to end the exposurecalculation processing BB3 in FIG. 25. The operation proceeds to stepS535 if the flash quantity is too large.

In step S535, the arithmetic operation circuit 101 sets the flashquantity h to be achieved at the external flash unit 11 equal to theminimum flash quantity value hmin, and then the operation proceeds tostep S536. In step S536, the arithmetic operation circuit 101 calculatesthe control aperture value AVc as indicated in (10) below beforeproceeding to step S515.

AVc=MAVc+log₂(hmin/Mh)  (10)

In step S541 in FIG. 26, to which the operation proceeds after making anegative decision in step S504 as described above, the arithmeticoperation circuit 101 sets 3 (F2.8 (full open aperture)) for the controlaperture value AVc before proceeding to step S542. In step S542, thearithmetic operation circuit 101 makes a decision as to whether or notthe exposure value EV is smaller than −2. The arithmetic operationcircuit 101 makes an affirmative decision in step S542 if EV<−2 is trueto proceed to S 543, whereas it makes a negative decision in step S542if EV<−2 is not true, to proceed to step S545. The operation proceeds tostep S543 if the exposure value is beyond the control range of thecamera.

In step S543, the arithmetic operation circuit 101 sets −5 (30 sec) forthe control shutter speed TVc before proceeding to step S544.

In step S545, the arithmetic operation circuit 101 sets a value obtainedby subtracting 3 (F2.8) from the exposure value EV for the controlshutter speed TVc before the operation proceeds to step S544.

Since the processing executed in step S544 and steps S546 through S550is identical to the processing executed in step S508 and steps S510through S514 explained earlier, its explanation is omitted. Once theprocessing in step S550 is completed, the arithmetic operation circuit101 proceeds to step S515 in FIG. 25.

Since the processing executed in steps S551 through S553 is identical tothe processing executed in steps S526 through S528 explained earlier,its explanation is omitted. Once the processing in step S553 iscompleted, the arithmetic operation circuit 101 proceeds to step S515 inFIG. 25.

Since the processing executed in steps S554 through S561 is identical tothe processing executed in steps S529 through S536 explained earlier,its explanation is omitted. Once the processing in step S558 or S561 iscompleted, the arithmetic operation circuit 101 proceeds to step S515 inFIG. 25.

In step S571 in FIG. 27, to which the operation proceeds after making anegative decision in step S503 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not the modeparameter M is currently set to 1. The arithmetic operation circuit 101makes an affirmative decision in step S571 if M=1 (the shutter speedpriority automatic exposure mode) to proceed to step S572, whereas itmakes a negative decision in step S571 if M≠1 (a mode other than theshutter speed priority automatic exposure mode, i.e., either the A modeor the M mode in this case) to proceed to step S601 in FIG. 28.

In step S572, the arithmetic operation circuit 101 sets a value obtainedby subtracting the control shutter speed TVc from the exposure value EVfor the control aperture value AVc before proceeding to step S573.

Since the processing executed in steps S573 through S581 is identical tothe processing executed in step S508 and steps S510 through S517explained earlier, its explanation is omitted. Once the processing instep S581 is completed, the arithmetic operation circuit 101 ends theexposure calculation processing 13133.

Since the processing executed in steps S582 through S584 is identical tothe processing executed in steps S519 through S521 explained earlier,its explanation is omitted. After making a negative decision in stepS582 or after completing the processing in step S584, the arithmeticoperation circuit 101 ends the exposure calculation processing BB3.

Since the processing executed in steps S585 through S587 is identical tothe processing executed in steps S526 through S528 explained earlier,its explanation is omitted. Once the processing in step S587 iscompleted, the arithmetic operation circuit 101 proceeds to step S579.

Since the processing executed in steps S588 through S595 is identical tothe processing executed in steps S529 through S536 explained earlier,its explanation is omitted. Once the processing in step S592 or S595 iscompleted, the arithmetic operation circuit 101 proceeds to step S579.

In step S601 in FIG. 28, to which the operation proceeds after making anegative decision in step S571 as described above, the arithmeticoperation circuit 101 makes a decision as to whether or not the modeparameter M is currently set to 2. The arithmetic operation circuit 101makes an affirmative decision in step S601 if M=2 (the aperture priorityautomatic exposure mode) to proceed to step S602, whereas it makes anegative decision in step S601 if M≠2 (a mode other than the aperturepriority automatic exposure mode, i.e., the m mode in this case),thereby ending the exposure calculation processing BB3.

In step S602, the arithmetic operation circuit 101 sets a value obtainedby subtracting the control aperture value AVc from the exposure value EVfor the control shutter speed value TVc before proceeding to step S603.

Since the processing executed in steps S603 through S606 is identical tothe processing executed in steps S483 through S486 explained earlier,its explanation is omitted. Once the processing in step S604 or S606 iscompleted, the arithmetic operation circuit 101 ends the exposurecalculation processing BB3.

The third embodiment described above is now summarized.

The adjustment for the change in the exposure (the value determined incorrespondence to the shutter speed, the aperture value and theimage-capturing sensitivity) of the background resulting from a changein the sensitivity level adjusted to correct any excess/insufficiency offlash quantity from the flash unit is executed as described below.

(1) If the camera is set in the P mode (program automatic exposuremode), the adjustment for the change in the background exposure isachieved by altering at least either the aperture value or the shutterspeed.(2) If the camera is set in the S mode (the shutter speed priorityautomatic exposure mode), the adjustment for the change in thebackground exposure is achieved by altering the aperture value.(3) If the camera is set in the A mode (the aperture priority automaticexposure mode), the adjustment for the change in the background exposureis achieved by altering the shutter speed.(4) If the camera is set in the M mode (the manual exposure mode), noadjustment for the change in the background exposure is executed.

Since the adjustment for the change occurring in the background exposureis executed in a specific manner corresponding to the exposure modesetting, the background exposure can be adjusted in a desirable mannerwithout altering any settings against the intention of the photographer.

Instead of the processing in FIG. 28, the processing in FIG. 29 may beexecuted. In the processing in the flowchart presented in FIG. 29, anadjustment for the change in the background exposure is executed byaltering the shutter speed even when the camera is set in the M mode(manual exposure mode).

Furthermore, the processing shown in FIG. 30 may be executed as analternative to the processing in FIG. 28 or FIG. 29. In the processingshown in the flowchart in FIG. 30, the operation proceeds to step S572in FIG. 27 when the camera is set in the M mode (the manual exposuremode) to adjust for the change in the background exposure by changingthe aperture value.

Fourth Embodiment

FIG. 31 is a block diagram of the structure adopted in an electroniccamera 1 achieved in the first embodiment of the present invention. Inthe FIG. 31, which is similar to the FIG. 1 illustrating the firstembodiment, the same reference numerals are assigned to identicalcomponents. The electronic camera 1 includes an internal flash unit, andan external flash unit 11 is mounted at an accessory shoe (not shown).An arithmetic operation circuit 101 is constituted with a microcomputerand the like. The arithmetic operation circuit 101 executes specificarithmetic operations by using signals input thereto from various blocksto be explained later and outputs control signals generated based uponthe arithmetic operation results to the individual blocks. Thearithmetic operation circuit 101 further includes a communicationcircuit (not shown) which enables the arithmetic operation circuit 101to communicate with the external flash unit 11.

An image-capturing element 121 is constituted with a CCD image sensor orthe like. The image-capturing element 121 captures an image formed withsubject light having passed through an interchangeable lens L used forphotographing operations and outputs an image-capturing signal to an A/Dconversion circuit 122. The A/D conversion circuit 122 converts theanalog image-capturing signal to a digital signal The image-capturingelement 121 and the A/D conversion circuit 122 are driven so as tooperate with specific timing by drive signals output from a timingcircuit 124.

An image processing circuit 123 may be constituted with an ASIC or thelike. In addition to executing image processing such as white balanceprocessing on image data resulting from the digital conversion, theimage processing circuit 123 executes compression processing forcompressing the image data having undergone the image processing in apredetermined format, decompression processing for decompressingcompressed image data and the like. In a buffer memory 125, image datato be processed at the image processing circuit 123 are temporarilystored. A recording medium 126 may be a detachable memory card that canbe loaded into and unloaded from the camera freely, for instance. Theimage data having undergone the image processing are recorded into therecording medium 126.

A position detection switch SW1 is a micro switch that detects theposition of the internal flash unit (not shown), i.e., whether it is ata storage position or it has been popped up to an operating position bya pop-up mechanism (not shown). A light emitting unit 44 is included inthe internal flash unit. A position detection switch SW1 outputs an ONsignal when the internal flash unit is at the operating position andoutputs an OFF signal when the internal flash unit is at the storageposition.

An internal flash unit light emission circuit 102 executes lightemission control by issuing a light emission start instruction and alight emission stop instruction for the light emitting unit 44 in theinternal flash unit in response to commands from the arithmeticoperation circuit 101. The internal flash unit light emission circuit102, which includes a charge circuit (not shown), starts a charge uponreceiving a command from the arithmetic operation circuit 101 andoutputs a complete signal as the charge is completed.

A photometering device 103 detects the quantity of the subject lightpassing through the photographic lens L and outputs a detection signalto the arithmetic operation circuit 101. The photometering device 103also has a function of a photo sensor and receives the light having beeninitially emitted from the internal flash unit or an external flash unit11 and reflected at the subject. For instance, it receives the lightreflected from the subject during a preliminary light emission executedprior to a photographing operation, executes a time integration of thelight receiving signal and outputs the time-integrated value to thearithmetic operation circuit 101. It is to be noted that a flash-sensorelement 131 may be provided as a dedicated sensor separately from thephotometering device 103. Alternatively, the image-capturing element 121may fulfill three functions, i.e., the image-capturing function, thefunction of the photometering device 103 and the function of theflash-sensor element 131.

A focal point detection device 104 detects the state of the adjustmentof the focal point position achieved with the photographic lens L andoutputs a detection signal to the arithmetic operation circuit 101.

A shutter release switch SW6 interlocking with a shutter releaseoperation button (not shown) outputs a shutter release operation signalto the arithmetic operation circuit 101. The operation signal may be ahalfway press operation signal corresponding to a halfway pressoperation of the shutter release operation button or a full pressoperation signal corresponding to a full press operation through whichthe shutter release operation button is pressed further down than in thehalfway press operation. At a display device 118, a display indicating acharge completion is brought up when the charge of the internal flashunit or the external flash unit 11 is completed. Photographinginformation such as the shutter speed and the aperture value and warningicons indicating over-exposure and under-exposure are also displayed atthe display device 118.

The front curtain and the rear curtain (not shown) at a shutter 115 areheld and released independently of each other under control implementedby a shutter drive circuit 114. An X contact point switch SW5 enters anON state and outputs an ON signal as the front curtain at the shutter115 completes its run, and enters an OFF state and outputs an OFF signalhalfway through a charge of the shutter 115. An aperture positiondetection device 116 detects the aperture position corresponding to theaperture value and outputs a detection signal to the arithmeticoperation circuit 101. An aperture holding device 117 stops the aperturebeing driven and holds the aperture at the position corresponding to aspecific aperture value.

A motor drive circuit 112 implements drive control on a sequence motor113 in response to a command from the arithmetic operation circuit 101.The sequence motor 113, which constitutes a sequence drive device (notshown), raises/lowers a mirror (not shown), drives the aperture (notshown), charges the shutter 115 and the like. A sequence switch SW4,which is also part of the sequence drive device mentioned above,generates, for instance, the timing with which braking of the sequencemotor 113 is controlled.

A lens drive device 105 adjusts the focal point position of thephotographic lens L by driving a focus lens (not shown) in thephotographic lens L forward/backward along the optical axis in responseto a command issued by the arithmetic operation circuit 101.

A custom setting operation member 119 outputs an operation signalcorresponding to a custom setting operation to the arithmetic operationcircuit 101. The arithmetic operation circuit 101 sets and clears animage-capturing sensitivity automatic adjust mode in response to thecustom setting operation signal. In the image-capturing sensitivityautomatic adjust mode, the image-capturing sensitivity SV (exposuresensitivity) is automatically adjusted when calculating the controlexposure so as to move toward the optimal exposure. When theimage-capturing sensitivity automatic adjust mode is cleared, thecontrol exposure is calculated to adjust toward the optimal exposurewithout altering the current image-capturing sensitivity setting SV. Itis to be noted that in the following explanation, the automaticadjustment of the image-capturing sensitivity effected while utilizing aflash unit is referred to as an image-capturing sensitivity automaticcorrection.

The custom setting operation member 119 is also used to set an exposurecorrection quantity and a flash control correction quantity to bedetailed later.

A sensitivity setting operation member 110 outputs an operation signalto the arithmetic operation circuit 101 in response to animage-capturing sensitivity setting operation. The arithmetic operationcircuit 101 adjusts the setting for the image-capturing sensitivity atthe image-capturing element 121 based upon the image-capturingsensitivity setting operation signal input thereto. The image-capturingsensitivity may be selected in specific steps within a range equivalentto, for instance, ISO 100 to ISO 1600.

The external flash unit 11 includes a controller 201, a light emissioncircuit 202, a light emitting unit 11 a, a setting operation member 203and a display device 204. As the external flash unit 11 is mounted atthe accessory shoe (not shown) at the camera body 1, the arithmeticoperation circuit 101 at the camera body 1 and the external flash unit11 become connected through contact point terminals 10 a, 10 b and 10 c.The contact point terminal 10 a is a terminal for an X contact pointsignal generated through the X contact point switch SW5. The X contactpoint signal is output to the controller 201 via the contact pointterminal 10 a while a signal output is allowed by the arithmeticoperation circuit 101 but is not output to the controller 201 if thesignal output is prohibited. The contact point terminal 10 b is a GNDterminal provided to equalize the electrical ground potentials at thecamera body 1 and the external flash unit 11. The contact point terminal10 c is a communication terminal through which the camera body 1 and theexternal flash unit 11 communicate with each other.

The controller 201 is constituted with a microcomputer and the like. Thecontroller 201 executes specific arithmetic operations by using signalsinput thereto from various blocks in the external flash unit 11 andoutputs control signals generated based upon the arithmetic operationresults to the individual blocks in the external flash unit 11. Inaddition, the controller 201 engages in communication with thearithmetic operation circuit 101 via the contact point terminal 10 c toreceive information from the arithmetic operation circuit 101 indicatinga flash quantity to be achieved and also to transmit informationindicating the specific light emission mode set at the external flashunit 11. The controller 201 also issues a light emission instruction forthe light emission circuit 202 upon receiving sensor X contact point ONsignal via the contact point terminal 10 a.

The light emission circuit 202 implements light emission control byissuing a light emission start instruction and a light emission stopinstruction for the light emitting unit 11 a of the external flash unit11 in response to commands issued by the controller 201. The lightemission circuit 202, which includes a charge circuit (not shown),starts a charge as the power switch (not shown) at the external flashunit 11 is turned on and outputs a complete signal to the controller 201as the charge is completed.

A setting operation member 203 is a switch through which the lightemission mode and the like are set. The light emission mode includes aTTL automatic flash control mode and a manual light emission mode. Inthe TTL automatic flash control mode, the illuminating light having beenemitted from a flash unit and then reflected from the subject isreceived at the photometering device 103 through the lens L andautomatic flash control is executed to control the flash quantity fromthe flash unit based upon the quantity of the received light. In themanual light emission mode, the flash unit emits light to achieve theflash quantity having been set with the setting operation member 203.

At a display device 204, a display indicating a charge completion isbrought up when the charge of the external flash unit 11 is completed.Information indicating the current light emission mode setting is alsodisplayed at the display device 204.

The camera operation processing executed at the arithmetic operationcircuit 101 of the electronic camera 1 is now explained in reference tothe flowchart presented in FIG. 32. The program in conformance to whichthe processing in the flowchart presented in FIG. 32 is executed isstarted up as a halfway press operation signal is input to thearithmetic operation circuit 101 from the shutter release switch SW6while the main switch of the electronic camera 1 is in an ON state.

In step S701 in FIG. 32, the arithmetic operation circuit 101 makes adecision as to whether or not a predetermined length of time has elapsedsince the halfway press operation signal was input. The arithmeticoperation circuit 101 makes an affirmative decision in step S701 if atimer (not shown) which starts a time count immediately after a halfwaypress operation has counted up to the predetermined length of time andthen has gone off, and in this case, the operation returns to the state(the halfway press operation wait state) prior to the startup of theprocessing shown in FIG. 32. If, on the other hand, the halfway presstimer has not gone off yet (the time count of the predetermined lengthof time is still in progress or the halfway press operation is stillbeing performed), the arithmetic operation circuit 101 makes a negativedecision in step S701 to proceed to step S702.

In step S702, the arithmetic operation circuit 101 monitors the state ofthe shutter release button to determine whether or not it has beenpressed all the way down. The arithmetic operation circuit 101 makes anaffirmative decision in step S702 if a full press operation signal hasbeen input to proceed to execute the shutter release sequenceprocessing, as shown in FIG. 33. The shutter release sequence processingis to be described in detail later. If, on the other hand, no full pressoperation signal has been input, the arithmetic operation circuit 101makes a negative decision in step S702 to proceed to step S703.

In step S703, the arithmetic operation circuit 101 measures the subjectbrightness and then the operation proceeds to step S704. Morespecifically, it obtains brightness information corresponding to each ofthe specific areas of the photographic field defined by dividing thephotographic field based upon detection signals input from thephotometering device 103 and then calculates a brightness value BVansrepresenting the entire photographic scene by incorporating theindividual sets of brightness information corresponding to the differentareas so as to achieve optimal exposure for the photographic scene.Since such representative brightness value calculation is executed byusing an algorithm of the known art, a detailed explanation is notprovided.

In step S704, the arithmetic operation circuit 101 calculates a shutterspeed TV and an aperture value AV that will achieve an exposure quantityclose to the optimal exposure in correspondence to the brightness valueBVans, the current image-capturing sensitivity setting, the currentexposure correction quantity setting and the current exposure modesetting, before proceeding to step S705. More specifically, it adjustsTV and AV so as to set the value of (TV+AV) as close as possible to(BVans+SV0−RH) within the control limit range. SV0 (=log₂(0.32×ISOsensitivity)) represents the image-capturing sensitivity setting, RH(unit: steps) represents the exposure correction quantity, TV(=log₂(shutter speed)) represents the shutter speed and AV (=log_(√2)(Fnumber)) represents the aperture value, all indicated by using apexvalues.

The exposure correction quantity is set to increase/decrease theexposure quantity relative to the optimal value. One of the followingmodes is selected for the exposure mode.

1. An aperture priority exposure mode in which the shutter speed isautomatically adjusted at a fixed aperture value setting.2. A shutter priority exposure mode in which the aperture value isautomatically adjusted at a fixed shutter speed setting.3. A program mode in which the aperture value and the shutter speed areautomatically adjusted so that the extent of changes in the aperturevalue and the shutter speed achieve a predetermined ratio.4. A mode in which control is implemented at the current aperture valuesetting and the current shutter speed setting.

It is to be noted that the ratio to be achieved in the program mode isvaried in accordance to the mode set for the specific photographicscene, i.e., in accordance to a specific category setting such as alandscape mode, a portrait mode or a night-time photographing mode.

The values obtained through the exposure calculation (step S704) arecontrolled at all times to stay within their control limit ranges. Thecontrol limit range of the aperture value is determined by the maximumaperture value and the minimum aperture value. The control limit rangeof the shutter speed is determined in correspondence to the high shutterspeed limit and the low shutter speed limit. If the shutter speed needsto be controlled within a predetermined range during a light emission ata flash unit, the shutter speed is also determined in correspondence tothe maximum speed and the minimum speed of this predetermined range.

In step S705 in FIG. 32, the arithmetic operation circuit 101 calculatesthe extent of over-exposure or under-exposure (ambient light over/underextent) dDC manifesting when exposure (ambient light exposure) isachieved with surrounding light (light from the sun, indoor lighting orthe like, hereafter referred to as ambient light) other than flash lightemitted at a flash unit as indicated in (12) below, and then theoperation proceeds to step S706.

dDC=BVans+SV0−RH−AV−TV  (12)

If dDC=0, optimal exposure is achieved with ambient light, instead ofmanifesting over-exposure or under-exposure. With TV or AV controlledwithin the control limit ranges during the exposure calculation in stepS704, it may not always be possible to set dDC to 0. For instance, ifthe aperture value is controlled so as to remain the minimum aperturevalue when, in fact, it is more desirable to control the aperture valueto a level lower than the minimum aperture value, dDC will assume apositive value resulting in ambient light over-exposure.

In addition, if the shutter speed is controlled so as not to becomeslower than a predetermined value during a light emission at a flashunit in a mode other than a slow synchronous mode, the shutter speed isnot allowed to be lower than the low shutter speed limit even when it ismore desirable to set a lower shutter speed, and in this case, dDCassumes a negative value to result in ambient light under-exposure.While optimal exposure is achieved for the main subject with the flashlight, the background is underexposed in an image photographed underthese conditions.

In step S706, the arithmetic operation circuit 101 makes a decision asto whether image-capturing sensitivity automatic control is on or off.The arithmetic operation circuit 101 makes an affirmative decision instep S706 if the image-capturing sensitivity automatic adjust mode iscurrently set to proceed to step S707, whereas it makes a negativedecision in step S706 if the image-capturing sensitivity automaticadjust mode has been cleared to proceed to step S710.

In step S707, the arithmetic operation circuit 101 makes a decision asto whether or not the camera is in a photographing state in which animage is photographed with light emitted at a flash unit. The arithmeticoperation circuit 101 makes an affirmative decision in step S707 if theinternal flash unit (not shown) has been popped up to the operatingposition or the external flash unit 11 mounted at the accessory shoe(not shown) of the camera body 1 has been turned on and, in this case,the operation returns to step S701. If, on the other hand, the internalflash unit (not shown) has not been popped up and the external flashunit 11 is not mounted or the power to the external flash unit has notbeen turned on, the arithmetic operation circuit 101 makes a negativedecision in step S707 to proceed to step S708.

In step S708, the arithmetic operation circuit 101 executes an automaticadjustment of the image-capturing sensitivity as indicated in (13) belowbased upon the ambient light over/under extent dDC, and then theoperation proceeds to step S709.

SVt=−dDC  (13)

ΔSVt represents the extent to which the image-capturing sensitivity isto be increased/decreased relative to the image-capturing sensitivitysetting SV0. The range over which ΔSVt can be adjusted through theimage-capturing sensitivity automatic adjustment is restricted toSVmin≦(SV0+ΔSVt)≦SVmax. SVmin is the lowest image-capturing sensitivitylevel in the control range and SVmax is the highest image-capturingsensitivity level in the control range.

In step S709, the arithmetic operation circuit 101 calculates an imagesensitivity level SV1 to be achieved without emitting flash light asindicated in (14) below and sets the calculated image-capturingsensitivity SV1 at the image-capturing element 121 before returning tostep S701. As a result, the image-capturing sensitivity at theimage-capturing element 121 is switched from the current setting, i.e.,the value SV0.

SV1=SV0+ΔSVt  (14)

In step S710, to which the operation proceeds after making a negativedecision in step S706 as described above, the arithmetic operationcircuit 101 sets the image-capturing sensitivity setting SV0 into theimage-capturing sensitivity SV1, and then the operation returns to stepS701. As a result, the value SV0 currently set for the image-capturingsensitivity at the image-capturing element 121 is sustained.

The shutter release sequence processing is now explained in detail inreference to the flowchart presented in FIG. 33. In step S721, thearithmetic operation circuit 101 makes a decision as to whether or not aflash unit is in a light emission enabled state. The arithmeticoperation circuit 101 makes an affirmative decision in step S721 if theinternal flash unit (not shown) has been popped up to the operatingposition or the external flash unit 11 mounted at the accessory shoe(not shown) of the camera body 1 has been turned on and, in this case,the operation proceeds to step S731. If, on the other hand, the internalflash unit (not shown) has not been popped up and the external flashunit 11 is not mounted or the power to the external flash unit 11 hasnot been turned on, it makes a negative decision in step S721 to proceedto step S722.

In step S722, the arithmetic operation circuit 101 issues instructionsto raise the main mirror and to adjust the aperture before proceeding tostep S723. The aperture value to which the aperture is to be adjusted(namely, the aperture value indicated to the aperture holding device117) is the aperture value AV having been calculated in step 9704.

In step S723, the arithmetic operation circuit 101 issues instructionsto drive the shutter 115 and to store an electrical charge at theimage-capturing element 121 before proceeding to step S724. The shutterspeed indicated in the instruction (namely, the shutter speed indicatedto the shutter drive circuit 114) is the shutter speed TV having beencalculated in step S704. The image-capturing element 121 captures animage at the image-capturing sensitivity SV1 set for the operationexecuted without flash light.

In step S724, the arithmetic operation circuit 101 issues instructionsto lower the main mirror and to open the aperture before proceeding tostep S725. In step S725, the arithmetic operation circuit 101 outputsinstructions to execute specific image processing on the image dataobtained through the image-capturing operation and to execute processingfor recording the image data having undergone the image processing intothe recording medium 126, before ending the shutter release sequenceprocessing in FIG. 33.

In step S731 to which the operation proceeds after making an affirmativedecision in step S721 as described above, the arithmetic operationcircuit 101 issues an instruction for the flash unit to execute apreliminary light emission (flash light emission) and also issues aninstruction (a reflected flash light metering instruction) for thephotometering device 103 to execute a time integration of thepreliminary flash light reflected at the subject and then received atthe photometering device before proceeding to step S732. An output(hereafter referred to as a measured preliminary flash light value)indicating the time-integrated value of the reflected flash light havingbeen emitted through the preliminary light emission is used in anarithmetic operation executed to calculate the required flash quantityfor the flash light emission during the photographing operation(hereafter referred to as a main light emission) and is also used in anarithmetic operation executed to calculate the image-capturingsensitivity automatic correction quantity for the flash light emission.When measuring the reflected flash light having been emitted through thepreliminary light emission, the measured ambient light value issubtracted from the photometering output corresponding to thepreliminary light emission so as to exclude the component attributableto the ambient light and to measure the reflected light component fromthe flash light emission alone. Thus, the photometric value of the flashlight emitted in the preliminary flash light emission, which has beenreflected at the subject, can be ascertained with a high degree ofaccuracy.

It is to be noted that the flash unit that emits the light, is theinternal flash unit if the internal flash unit is at its operatingposition and is the external flash unit 11 if the external flash unit 11mounted at the accessory shoe (not shown) has been turned on. The flashquantity GVy achieved at the flash unit through the preliminary lightemission is indicated as in (15) below.

GVy=log_(√2)(GNy)  (15)

GNy in the expression above represents a preliminary light emissionguide number.

In step S732, the arithmetic operation circuit 101 calculates therequired flash quantity GVreq to be emitted from the flash unit duringthe main light emission as indicated in (16) below, and then theoperation proceeds to step S733.

GVreq=GVy−log₂(IG)+CH+OFFSET+(5−SV0)+AV−AV0  (16)

IG and CH in the expression above are respectively the value obtained byexecuting A/D conversion of the measured preliminary flash light valueand the flash control correction quantity (unit: step). OFFSETrepresents a constant term which is a value ascertained in advance basedupon the results of tests conducted so as to achieve a predeterminedflash quantity when a flash light emission is executed under standardconditions. SV0 is the current image-capturing sensitivity valuesetting, which is subtracted from 5 as indicated above since the flashquantity is calculated in reference to the level equivalent to ISO 100(SV=5). AV represents the apex value of the open aperture value, and AV0is subtracted from AV since the preliminary flash light metering isexecuted with the aperture set at the open position. In addition, therelationship expressed as in (17) below exists between the requiredflash quantity GVreq for the main light emission and the main lightemission guide number GNreq.

GVreq=log_(√2)(GNreq)  (17)

In step S733, the arithmetic operation circuit 101 makes a decision asto whether the image-capturing sensitivity automatic correction settingis on or off. The arithmetic operation circuit 101 makes an affirmativedecision in step S733 if the electronic camera is set for theimage-capturing sensitivity automatic correction (if the image-capturingsensitivity automatic adjust mode is currently set) to proceed to stepS734, whereas it makes a negative decision in step S733 if the camera isnot set for the image-capturing sensitivity automatic correction (if theimage-capturing sensitivity automatic adjust mode has been cleared) toproceed to step S751.

In step S734, the arithmetic operation circuit 101 calculates a requiredsensitivity correction quantity ΔSVreq based upon the required mainlight emission flash quantity GVreq and the light emission controlrange. The required sensitivity correction quantity SVreq represents theextent by which the image-capturing sensitivity needs to be corrected inorder to correct the excess/insufficiency of the exposure quantity inthe main light emission. The lower limit GVmin and the upper limit GVmaxof the light emission control range are predetermined design values.GVmin and GVmax of the internal flash unit are stored in memory in thearithmetic operation circuit 101, whereas GVmin and GVmax of theexternal flash unit 11 are provided to the arithmetic operation circuit101 through communication. The required sensitivity correction quantityASVreq is calculated as detailed below.

1. When GVmin≦GVreq≦GVmax, ΔSVreq=0 2. When GVreq<GVmin,ΔSVreq=GVreq−GVmin 3. When GVmax<GVreq, ΔSVreq=GVreq−GVmax

However, since control is implemented to ensure that the image-capturingsensitivity having undergone the image-capturing sensitivity automaticcorrection does not deviate from the control-enabled range, i.e., therange between the minimum image-capturing sensitivity SVmin and themaximum image-capturing sensitivity SVmax, the required sensitivitycorrection quantity ΔSVreq is in reality calculated as follows.

A When (SV0+ΔSVreq)<SVmin, ΔSVreq=SVmin−SV0 B When SVmax<(SV0+ΔSVreq),ΔSVreq=SVmax−SV0

Once the required sensitivity correction quantity ΔSVreq is calculated,the arithmetic operation circuit 101 proceeds to step S735.

In step S735, the arithmetic operation circuit 101 further corrects therequired sensitivity correction quantity ΔSVreq by using the ambientlight over/under extent dDC having been calculated in step S705 and thuscalculates the ultimate sensitivity correction quantity ΔSVs. Thesensitivity correction quantity ΔSVs is calculated as detailed below.

1 When ΔSVreq≦0, ΔSVs=ΔSVreq

2 When 0<ΔSVreq and 0≦dDC, ΔSVs=03 When 0<ΔSVreq, dDC<0 and −dDC≦ΔSVreq, ΔSVs=−dDC4 When 0<ΔSVreq, dDC<0 and ΔSVreq<−dDC, ΔSVs=ΔSVreq

Once the ultimate sensitivity correction quantity ASVs is calculated,the arithmetic operation circuit 101 proceeds to step S736.

In step S736, the arithmetic operation circuit 101 executes anarithmetic operation to calculate an image-capturing sensitivity levelSV2 for the flash photographing operation as indicated in (18) belowbefore proceeding to step S737.

SV2=SV0+ΔSVs  (18)

In step S737, the arithmetic operation circuit 101 sets or indicates amain light emission control quantity (required flash quantity) for theflash unit, and then the operation proceeds to step S738. The main lightemission control quantity is set at the internal flash unit lightemission circuit 102 if flash light emitted by the internal flash unitis being used, whereas the main light emission control quantity isindicated to the external flash unit 11 through communication if flashlight emitted by the external flash unit 11 is being used. The requiredflash quantity GVreq is set or indicated as detailed below.

1 When GVmin≦GVreq≦GVmax, the required main light emission flashquantity GVreq is set or indicated.2 When GVreq<GVmin, the lower limit GVmin of the light emission controlrange is set or indicated.3 When GVmax<GVreq, the upper limit GVmax of the light emission controlrange is set or indicated.

In step S738, the arithmetic operation circuit 101 issues instructionsto raise the main mirror and to adjust the aperture before proceeding tostep S739. The aperture value to which the aperture is to be adjusted(namely, the aperture value indicated to the aperture holding device117) is the aperture value AV having been calculated in step S704. It isto be noted that the processing in step S738 may be executed in parallelwhile the processing in steps S732 through S737 is in progress.

In step S739, the arithmetic operation circuit 101 sets theimage-capturing sensitivity SV2 at the image-capturing element 121 andissues instructions to drive the shutter 115 and to store electricalcharges at the image-capturing element 121 before proceeding to stepS724. The shutter speed indicated in the instruction (namely, theshutter speed indicated to the shutter drive circuit 114) is the shutterspeed TV having been calculated in step S704. The image-capturingelement 121 captures an image at the image-capturing sensitivity levelSV2 set for the operation executed with flash light. It is to be notedthat an X contact point signal is generated with predetermined timingwhen the shutter 115 is in a full open state, and that the internalflash unit (or the external flash unit 11) emits light insynchronization with the X contact point synchronous signal.

In step S751, to which the operation proceeds after making a negativedecision in step S733 as described above, the arithmetic operationcircuit 101 sets or indicates a main light emission control quantity(required flash quantity) for the flash unit. The main light emissioncontrol quantity is set at the internal flash unit light emissioncircuit 102 if flash light emitted by the internal flash unit is beingused, whereas the main light emission control quantity is indicated tothe external flash unit 11 through communication if flash light emittedby the external flash unit 11 is being used. The required flash quantityGVreq is set or indicated as described below.

1 When GVmin≦GVreq≦GVmax, the required main light emission flashquantity GVreq is set or indicated.2 When GVreq<GVmin, the lower limit GVmin of the light emission controlrange is set or indicated.3 When GVmax<GVreq, the upper limit GVmax on the light emission controlrange is set or indicated.

The arithmetic operation circuit 101 also sets the image-capturingsensitivity setting SV0 into the image-capturing sensitivity SV2 beforeproceeding to step S738. As a result, the value SV0 currently set forthe image-capturing sensitivity at the image-capturing element 121 issustained.

In the fourth embodiment described above, the ultimate sensitivitycorrection quantity ΔSVs is calculated by first determining through anarithmetic operation the extent of the over/under exposure (the ambientlight over/under extent) dDC attributable to the surrounding light(ambient light) other than light emitted from the flash unit and thencorrecting the required image-capturing sensitivity correction quantitySVreq, by which the image-capturing sensitivity needs to be corrected inorder to correct the over/under exposure during the main light emission,in correspondence to the value of dDC. As a result, the sensitivity iscorrected in a desirable manner for the main light emission (flash lightemission) and, at the same time, ambient light over/under exposure isprevented.

The advantages of the embodiment are summarized in correspondence to theindividual conditions.

1 When ΔSVreq≦0, ΔSVs is set equal to ΔSVreq.

When the required main light emission flash quantity GVreq is smallerthan the minimum flash quantity GVmin of the flash unit, the requiredsensitivity correction quantity ΔSVreq takes on a negative value. IfΔSVreq is equal to or smaller than 0, the ultimate sensitivitycorrection quantity ΔSVs is set equal to ΔSVreq to optimize the exposureof the main subject during the main light emission. Under thesecircumstances, the background and the like are exposed with the ambientlight in a desirable manner if ΔSVreq=0 but are underexposed ifΔSVreq<0.

2 When 0<ΔSVreq and 0≦dDC, LSVs is set to 0.

When the distance to the main subject is significant or the aperture hasbeen adjusted to a smaller diameter, the required sensitivity correctionquantity ΔSVreq takes on a positive value (toward a higherimage-capturing sensitivity level) if the required main light emissionflash quantity GVreq is greater than the maximum flash quantity GVmax ofthe flash unit. When 0≦dDC, the level of exposure achieved with ambientlight is either sufficient or excessive. If the image-capturingsensitivity is increased in order to correct under-exposure of the mainsubject during the main light emission, the level of the exposureachieved with the ambient light may become excessively high under thesecircumstances. Accordingly, the ultimate sensitivity correction quantityΔSVs is set to 0 to prevent ambient light over-exposure or to preventexacerbation of existing over-exposure under the ambient light. In otherwords, the image-capturing sensitivity is not corrected (adjusted) inthis situation.

3 When 0<ΔSVreq, dDC<0 and −dDC≦ΔSVreq, ΔSVs is set to −dDC

When dDC<0 and −dDC≦ΔSVreq, the extent of ambient light under-exposureis smaller than the extent of the under-exposure occurring during themain light emission. In this case, the ultimate sensitivity correctionquantity ΔSVs is adjusted in correspondence to the extent of the ambientlight under-exposure so as to prevent over-exposure under the ambientlight and to optimize the exposure of the main subject during the mainlight emission.

4 When 0<ΔSVreq, dDC<0 and ΔSVreq<−dDC, ΔSVs is set equal to ΔSVreq

When dDC<0 and ΔSVreq<−dDC, the extent of ambient light under-exposureis greater than the extent of the under-exposure occurring during themain light emission. In this case, the ultimate sensitivity correctionquantity ΔSVs is adjusted in correspondence to the required sensitivitycorrection quantity ΔSVreq so as to optimize the exposure of the mainsubject during the main light emission and to prevent ambient lightover-exposure with a high degree of reliability.

Fifth Embodiment

The fifth embodiment differs from the fourth embodiment in that theultimate sensitivity correction quantity ΔSVs is determined by takinginto consideration the flash control correction quantity CH. In stepS735 in FIG. 33, the arithmetic operation circuit 101 calculates thesensitivity correction quantity ΔSVs as detailed below. It is to benoted that the term “flash control correction” refers to an instance ofdeliberately altering the optimal flash quantity for the flash unitwhich is controlled through the flash control. For instance, the flashcontrol correction may be executed when the main subject needs to beilluminated brightly by further increasing the flash quantity or whenthe flash quantity needs to be reduced to avoid illuminating the mainsubject with intense light. The flash control correction quantity is setin advance by the photographer via the custom setting operation member119 or the like.

1 When ΔSVreq≦0, ΔSVs=ΔSVreq

2 When 0<ΔSVreq and 0≦dDC, ΔSVs=CH3 When 0<ΔSVreq, dDC<0 and −dDC≦ΔSVreq, ΔSVs=−dDC+CH4 When 0<ΔSVreq, dDC<0 and ΔSVreq<−dDC, ΔSVs=ΔSVreq

The processing executed in steps other than step S375 is identical tothe processing executed in the corresponding steps in the fourthembodiment.

When the ultimate sensitivity correction quantity ΔSVs is calculated byfirst executing an arithmetic operation to calculate the extent ofover-exposure/under-exposure (the ambient light over/under extent) dDCattributable to the surrounding light (ambient light) other than lightemitted from the flash unit and then correcting the requiredimage-capturing sensitivity correction quantity ΔSVreq by which theimage-capturing sensitivity needs to be corrected in order to correctthe over/under exposure for the main light emission in correspondence tothe value of dDC, the current flash control correction quantity settingis reflected in the exposure in the fifth embodiment. As a result, thesensitivity is corrected in an optimal manner for the flash lightemission and, at the same time, the over/under exposure manifestingunder the ambient light can be prevented. It is to be noted that theflash control correction quantity CH is also taken into considerationwhen calculating the required main light emission flash quantity GVreqas well.

The advantages of the fifth embodiment are now summarized incorrespondence to cases 2 and 3, in which the processing is executeddifferently from that in the fourth embodiment.

2 When 0<ΔSVreq and 0≦dDC, ΔSVs is set equal to CH

When 0≦dDC, the level of exposure achieved with ambient light is eithersufficient or excessive. If the image-capturing sensitivity is increasedin order to correct under-exposure of the main subject during the mainlight emission, the level of the exposure achieved with the ambientlight may become excessively high under these circumstances.Accordingly, the ultimate sensitivity correction quantity ΔSVs is set to(0+CH) and excessive over-exposure under the ambient light can beprevented.

3 When 0<ΔSVreq, dDC<0 and −dDC≦ΔSVreq, ΔSVs is set to (−dDC+CH)

When dDC<0 and −dDC≦ASVreq, the extent of ambient light under-exposureis smaller than the extent of the under-exposure occurring during themain light emission. In this case, the ultimate sensitivity correctionquantity ΔSVs is adjusted in correspondence to (extent of the ambientlight under-exposure+flash control correction quantity) so as to preventover-exposure under the ambient light and to optimize the exposure ofthe main subject during the main light emission.

While the data resulting from the image processing are recorded into therecording medium 126 in step S725 in the explanation provided above,data may be directly recorded into the recording medium 126 withoutundergoing the image processing.

The processing in step S725 may be started immediately of ter the imageis captured in step S723 and then be concurrently executed while theprocessing in step S723 is underway.

While the reflected flash light metering instruction is output to thephotometering device 103 in step S731, the reflected flash lightmetering instruction should be output to a flash-sensor element 131 ifthe flash-sensor element 131 is provided as a dedicated sensor inaddition to the photometering device 103. In addition, if theimage-capturing element 121 fulfills three functions, i.e., theimage-capturing function, the function of the photometering device 103and the function of the flash-sensor element 131, the reflected flashlight metering instruction should be output to the image-capturingelement 121.

While an explanation is given above on an example in which the maximumflash quantity that can be achieved during the main light emission isthe upper limit GVmax of the light emission control range, the actualflash quantity is reduced by the extent corresponding to the amount ofenergy used for the preliminary light emission, to be exact.Accordingly, the arithmetic operation may be executed to achieve an evenhigher degree of accuracy by using the upper limit GVmax*of the lightemission control range after the preliminary light emission as indicatedin (19) below.

GVmax*=log₂(2^((GVmax without preliminary light emission))−2^(GVy))  (19)

The above described embodiments are examples, and various modificationscan be made without departing from the spirit and scope of theinvention.

1-9. (canceled)
 10. An electronic camera, comprising: an image-capturingunit with variable image-capturing sensitivity, which captures an imageof a subject through a photographic lens; a brightness detection unitthat detects a subject brightness; a first calculation unit thatcalculates an ambient light over/under extent by using animage-capturing sensitivity set for the image-capturing unit, anexposure time length set for an image-capturing operation, an aperturevalue set for the image-capturing operation and the subject brightnesshaving been detected; a reflected light detection unit that detectsreflected light from a main subject when a flash unit, which executes amain flash to illuminate the subject during the image-capturingoperation and executes a preliminary flash emission to illuminate thesubject before the image-capturing operation, executes the preliminaryflash emission; a second calculation unit that calculates a main flashquantity needed for the image-capturing operation based upon a detectionsignal obtained at the reflected light detection unit during thepreliminary flash emission and the image-capturing sensitivity currentlyset for the image-capturing unit; a third calculation unit thatcalculates a sensitivity change quantity indicating an extent by whichthe currently set image-capturing sensitivity should be changed so as toachieve optimal exposure of the main subject with a main flash quantitywithin a variable flash quantity range of the flash unit if the mainflash quantity having been calculated by the second calculation unit isoutside the variable flash quantity range; and a sensitivity adjustingunit that adjusts the image-capturing sensitivity during theimage-capturing operation according to the sensitivity change quantityhaving been calculated by the third calculation unit; and a controldevice that controls the sensitivity adjusting unit so that the smallerthe ambient light over/under extent having been calculated by the firstcalculation unit is, the more strongly an extent of change in theimage-capturing sensitivity is restricted, in case that the sensitivitychange quantity indicates an increase from the currently setimage-capturing sensitivity.
 11. The electronic camera according toclaim 10, wherein: the first calculation unit calculates anunder-exposure extent; and the control device restricts an increase ofthe image-capturing sensitivity more strongly when the under-exposureextent is smaller than a predetermined value than when theunder-exposure extent is not smaller than the predetermined value. 12.An electronic camera, comprising: an image-capturing unit that capturesan image of a subject through a photographic lens; a sensitivity settingunit that sets an image-capturing sensitivity of the image-capturingunit; a first calculation unit that calculates an under-exposure extentunder ambient light; a second calculation unit that calculates a mainflash quantity needed for an image-capturing operation based upon theimage-capturing sensitivity currently set by the sensitivity settingunit and a detection signal obtained during a preliminary flash emissionby a flash unit; a third calculation unit that calculates a sensitivityincrease quantity from the image-capturing sensitivity currently set bythe sensitivity setting unit so as to achieve optimal exposure of thesubject when the flash unit executes a flash emission with a main flashquantity within a variable flash quantity range of the flash unit if themain flash quantity having been calculated by the second calculationunit is larger than the variable flash quantity range of the flash unit;and a control device that restricts an increase of the image-capturingsensitivity more strongly when the under-exposure extent calculated bythe first calculation unit is smaller than a predetermined value thanwhen the under-exposure extent calculated by the first calculation unitis not smaller than the predetermined value.
 13. An electronic camera,comprising: an image-capturing unit with variable image-capturingsensitivity, which captures an image of a subject through a photographiclens; a brightness detection unit that detects a subject brightness; afirst calculation unit that calculates an ambient light over/underextent by using an image-capturing sensitivity set for theimage-capturing unit, an exposure time length set for an image-capturingoperation, an aperture value set for the image-capturing operation andthe subject brightness having been detected; a reflected light detectionunit that detects reflected light from a main subject when a flash unit,which executes a main flash to illuminate the subject during theimage-capturing operation and executes a preliminary flash emission toilluminate the subject before the image-capturing operation, executesthe preliminary flash emission; a second calculation unit thatcalculates a main flash quantity needed for the image-capturingoperation based upon a detection signal obtained at the reflected lightdetection unit during the preliminary flash emission and theimage-capturing sensitivity currently set for the image-capturing unit;a third calculation unit that calculates a sensitivity change quantityindicating an extent by which the currently set image-capturingsensitivity should be changed so as to achieve optimal exposure of themain subject with a main flash quantity within a variable flash quantityrange of the flash unit if the main flash quantity having beencalculated by the second calculation unit is outside the variable flashquantity range; and a sensitivity adjusting unit that adjusts theimage-capturing sensitivity during the image-capturing operationaccording to the sensitivity change quantity having been calculated bythe third calculation unit; and a control device that controls thesensitivity adjusting unit so that an extent of change in theimage-capturing sensitivity is restricted according to the ambient lightover/under extent having been calculated by the first calculation unitin case that the sensitivity change quantity indicates an increase fromthe currently set image-capturing sensitivity.
 14. An electronic camera,comprising: an image-capturing unit with variable image-capturingsensitivity, which captures an image of a subject through a photographiclens; a brightness detection unit that detects a subject brightness; afirst calculation unit that calculates an ambient light over/underextent by using an image-capturing sensitivity set for theimage-capturing unit, an exposure time length set for an image-capturingoperation, an aperture value set for the image-capturing operation andthe subject brightness having been detected; a second calculation unitthat calculates a main flash quantity to be achieved at a flash unitwhich illuminates the subject during the image-capturing operation; athird calculation unit that calculates a correction quantity indicatingan extent by which the currently set image-capturing sensitivity shouldbe corrected so as to achieve optimal exposure of the subject with amain flash quantity within a variable flash quantity range if the mainflash quantity having been calculated by the second calculation unit isoutside the variable flash quantity range of the flash unit; and asensitivity adjusting unit that adjusts the currently setimage-capturing sensitivity based upon the correction quantity havingbeen calculated by the third calculation unit and the ambient lightover/under extent having been calculated by the first calculation unit.15. The electronic camera according to claim 14, further comprising: areflected light detection unit that detects reflected light from thesubject when the flash unit executes a preliminary flash emission,wherein: the second calculation unit calculates the main flash quantityneeded for an image-capturing operation based upon a detection signalobtained at the reflected light detection unit during the preliminaryflash emission and the image-capturing sensitivity currently set for theimage-capturing unit.
 16. The electronic camera according to claim 14,wherein: if the correction quantity indicates an increase from thecurrently set image-capturing sensitivity, the sensitivity adjustingunit adjusts the image-capturing sensitivity by restricting an extent ofchange in the image-capturing sensitivity in correspondence to theambient light over/under extent.
 17. The electronic camera according toclaim 14, wherein: if the correction quantity indicates an increase fromthe currently set image-capturing sensitivity and the ambient lightover/under extent indicates that sufficient ambient light is available,the sensitivity adjusting unit does not alter the image-capturingsensitivity.
 18. The electronic camera according to claim 14, wherein:if the correction quantity indicates an increase from the currently setimage-capturing sensitivity and an extent of ambient light insufficiencyindicated by the ambient light over/under extent is smaller than anextent of under-exposure corresponding to the correction quantity, thesensitivity adjusting unit adjusts the image-capturing sensitivity basedupon the ambient light over/under extent.
 19. The electronic cameraaccording to claim 14, wherein: if the correction quantity indicates anincrease from the currently set image-capturing sensitivity and anextent of ambient light insufficiency indicated by the ambient lightover/under extent is greater than an extent of under-exposurecorresponding to the correction quantity, the sensitivity adjusting unitadjusts the image-capturing sensitivity based upon the correctionquantity.
 20. The electronic camera according to claim 14, wherein: thesecond calculation unit corrects the main flash quantity incorrespondence to a flash control correction quantity currently set atthe camera; and the third calculation unit corrects the correctionquantity in correspondence to the currently set flash control correctionquantity.